DAN JONES: For me a great British castle is a fortress, a palace, a home.

And a symbol of power, majesty and fear.

For nearly a thousand years, castles have shaped Britain's famous landscape.

These magnificent buildings have been home to some of the greatest heroes and villains in our national history.

And many of them still stand proudly today, bursting with incredible stories of warfare, treachery, intrigue and even murder.

Join me, Dan Jones, as I uncover the secrets behind six great British castles.

This time, I'm in Stirling.

For centuries, this castle divided the warring nations of England and Scotland.

But ultimately, it was the key to uniting them to make Britain as we know it today.

The Forth Rail Bridge is one of Scotland's most famous sights.

It's big, it's red, and it takes a very long time to paint.

But it's more than just a pretty piece of engineering.

This bridge connects or divides the Scottish Highlands and the rest of the kingdom.

In the Middle Ages, the Forth estuary was known as the Scottish Sea.

It was wide and inaccessible and the land on the other side was known as Scotia ultra marina, Scotland beyond the sea.

Controlling the crossing of this river was the key to controlling the whole of Scotland.

And if you wanted to get beyond the sea, you had to cross the river.

But in the Middle Ages, you couldn't just hop on the train.

You had to walk or ride 34 miles along the river bank to this place.

The city of Stirling was known as the gateway to the Highlands, and for good reason.

For centuries, the first point upstream where you could cross the River Forth was here at Stirling.

The old medieval bridge was only a few feet away, but it was so narrow that only two men could cross it at a time.

You couldn't control Scotland without controlling Stirling Bridge.

Something that important, needed to be protected.

Legend has it that everyone from the Romans to King Arthur built the first castle at Stirling.

It's not hard to see why.

It's high on a volcanic crag and surrounded on three sides by steep cliffs.

And it commands the crossing of the river.

In fact, the first man to fortify it was the Scottish king Alexander I in the 12th century.

It soon became a favorite royal palace, and each generation for the next 600 years added new walls, turrets and buildings.

Stirling was built to be unbreakable.

And in the late 13th century, it was put to the test for the first time.

In 1286, King Alexander III died without a male heir.

The crown of Scotland fell into dispute.

Fourteen men claimed the throne.

So the Scots invited their neighbor, Edward I of England, to mediate.

It was a bad move.

Instead of trying to help, Edward invaded Scotland and tried to conquer it.

The war he began lasted almost a century and claimed tens of thousands of lives.

One of its most famous battles was fought directly below the castle, which was in English hands.

It was the Battle of Stirling Bridge.

By 1296, Edward I had given up on mediation and switched into full conquest mode.

He sent 6,000 men to this side of the river, because waiting on the other side on top of that hill was a man called William Wallace, who history or cinema has remembered as Braveheart.

Wallace was an obscure, small-time nobleman.

But he knew how to fight in Scotland and win.

He relied on smart tactics and making the most of local terrain.

Which was just as well, because on September 11, 1297, the whole future of Scotland depended on Wallace and a tiny force of loyal men defending Stirling Bridge.

The English were a well- organized army with hundreds of cavalry.

The Scots were mainly infantry.

But on the morning of the battle there were three problems.

First, the bridge was so narrow, the English could only cross two by two.

Secondly, the bridge came out on a narrow spit of land formed by a horseshoe in the river, and third, William Wallace attacked early.

There were almost 6,000 English soldiers, but only some of them had crossed the bridge when Wallace attacked.

The English army was now split between the two ends of the bridge.

The Scots swooped on the cavalry that had crossed and began to run them through with their spears.

Then it got worse for the English.

The land they marched onto was soft and muddy and not suitable for heavily armored horses and riders.

The Scots captured the bridgehead and slaughtered the English who were trapped behind their lines.

Those left on the English side, bottled it and ran away.

One of the English leaders, Hugh de Cressingham was flayed.

His skin was divided up as trophies and William Wallace supposedly used some of it to make a belt for his sword.

For the English, this was a total disgrace.

They lost over half their army to a ragtag force of peasants and part-timers.

They abandoned the castle to Wallace.

Edward I was humiliated.

And he would take terrible revenge.

He spent years hunting Wallace, eventually bringing him to London to be hanged, drawn and quartered.

Meanwhile, the war dragged on.

In 1303, Edward launched another military campaign right into the heart of Scotland.

This time the Scots occupied Stirling.

The English king didn't just want to kick them out, he wanted to teach them a lesson they wouldn't forget.

Edward knew that taking this castle was far too important to leave to his minions.

So he decided to come himself.

And he decided to bring with him the biggest and most feared weapon in the medieval world.

(MAN SHOUTS) At the start of the 14th century, Stirling Castle, the toughest fortress in Scotland, was about to face the meanest military machine in medieval history.

The siege began on the 21st of April, 1304.

Inside the castle was William Oliphant and a handful of men, but outside was the entire might of Edward I's army.

The English had 17 siege engines, including one weapon bigger than anything that had ever been seen before.

The castle was about to take a battering.

But it wasn't just shock-and-awe tactics, this was also public entertainment.

It was a spectator event.

So stands had been built for onlookers.

The Queen's apartments had a specially large window cut into them so she could watch what was going on.

And the siege engines had been given special nicknames, Lincoln, the Vicar, Segrave, Kingston, but the biggest attraction of all was War Wolf.

War Wolf was the largest catapult, or trebuchet, that had ever been conceived.

It was built outside the castle walls and took 50 carpenters at least three months to complete.

In July 1304, War Wolf was ready.

It really was a monster.

In the thick of war, this would be a terrifying thing to see.

I honestly cannot imagine what it must have felt like.

You're under siege, your food's running short, and then suddenly all these carts start arriving on the field and then they start to assemble outside the front of the castle -these great siege engines.

-Yeah.

PRIOR: And you know within two or three days that your castle is going to be pounded into oblivion by huge stone balls flying through the air.

It must have been terrifying.

And what are we firing, I mean, what, stones?

Fire?

What's coming out the end of it?

So, cattle carcasses, diseased cattle carcasses, the remains of your enemy, you catch people that have come out of the castle on sorties, behead them and fling the heads back over the wall, and very often the heads would go back over with wall with notes attached.

And the other thing is Greek fire, no one really knows what it was, we've lost the recipe for it, pine resin, naphtha, saltpeter.

Essentially it was something that would just continue to burn, so probably some kind of petroleum-based or tar-based substance that was sticky, that would float, that would stick to everything and just keep burning.

A bit like some medieval napalm.

Yes, that's exactly what it is.

That's exactly what it is, and it would stick to everything and just burn and burn and burn.

And you know, once you get fire in a castle, it's, you know... It's a lethal combination.

JONES: When the garrison saw this beast being assembled, they did what any sane human being would do, they surrendered.

But Edward was having none of it.

He'd built his toy, he wanted to use it, and he ordered them to stay in the castle until he was ready to fire.

The guys are gonna get out and get on the brakes.

If you need it slowing down at any point... Okay.

...tell these guys here and they will just put a little bit of pressure on the brakes and it will slow down and you will be fine.

-Just remember to keep walking fast.

-Keep walking.

Just keep on walking and you'll be fine.

Super, stylish.

WOMAN: Guys, are you ready?

MEN: Ready!

WOMAN: Grinders, are you ready?

BOTH: Born ready!

(WOMAN SHOUTING INDISTINCTLY) There you go.

Oh, this is a strange sensation.

JONES: Trebuchets use massive counterweights to rotate a throwing arm loaded with a projectile.

The shooting process uses brute manpower to raise the counterweight.

With a machine this size, that's a lot of manpower.

WOMAN: Fire in the hole!

-One down done?

-(EXHALES) -Is it all the way down?

-No, it's half way.

Bloody hell.

-All right?

-I know how a hamster feels.

-(PANTING) -(LAUGHING) Are we nearly there yet?

Oh, getting there.

(WOMAN SHOUTING INDISTINCTLY) (PANTING) WOMAN: Prepare to load!

It's live.

-We did that.

-Yeah.

When you drop the box, you flip the arm and away goes your projectile.

Well, I shall take a certain personal satisfaction in seeing this one go.

Load!

WOMAN: Fire!

Fire!

Fire again!

(WHOOSHING) Good God!

-Oh!

-(LAUGHING) JONES: A single shot from War Wolf completely destroyed the castle's gatehouse.

Stirling was in English hands again.

But the victory was short-lived.

Three years later, Edward was dead.

His hapless son Edward II became king of England.

And the Scots came roaring back.

They retook nearly every castle.

Only Roxburgh, Edinburgh, Berwick and Stirling remained.

They did it thanks to one of the most famous kings in their entire history, Robert the Bruce.

Bruce was a tough, shrewd soldier.

In spring 1314, he sent his brother to put Stirling Castle under siege and flush the English out.

In June, Edward II marched an army north to relieve the castle.

By June the 22nd, Edward was only 15 miles away at Falkirk, and it seemed like nothing was going to stop him from relieving Stirling Castle.

Only one thing stood in his way, Bannockburn.

The Battle of Bannockburn was fought within sight of Stirling Castle on boggy ground near the River Forth.

It was the most notorious clash in the War of Scottish Independence and one of the most celebrated moments in the whole of Scottish history.

On one side was a Scottish army of around 6,000 infantry and 500 cavalry, under Robert the Bruce.

On the other, was 15,000 English infantry and over 2,000 mounted troops.

The only possible outcome seemed to be a crushing victory for the invaders.

To defend against the English cavalry, Bruce divided his troops into schiltrons.

These were tightly packed groups bristling with pikes and virtually impregnable to a heavy horse charge.

The English fell into their trap.

They charged the schiltrons and their horsemen were impaled on Scottish spears.

Unable to hold formation, they broke ranks and fled.

(BLOWING WHISTLE) The English weren't just defeated, they were crushed, humiliated.

Their knights gored by the Scottish spears and others trampled to death quite literally in a river of blood.

And amidst all this chaos and this carnage, the English king Edward II turned and fled.

And when Robert the Bruce took possession of the castle, he did what he always did.

He destroyed it, so it would be of no use to his enemies again.

Bruce has a statue outside Stirling today, but when he'd finished with the castle in 1314, its towers and defenses had been torn down and its buildings burned.

For more than 20 years, this mighty fortress was a useless shell.

But Scotland's great stone guardian would rise again.

And from within its walls would come one of British history's most dangerous figures.

Not a warrior, but a woman.

Her name was Mary Queen of Scots.

In the late 14th century, Stirling Castle was a wreck.

It had survived attacks by English armies, but a Scottish king, Robert the Bruce, had burned it to the ground.

But the castle was soon reborn.

Its patrons were the Stuart family, a line of kings who rose to rule not only Scotland, but all of Britain.

Today, the oldest parts of Stirling Castle date from the 1380s, when the Stuarts first held it.

The family repaired and reinforced the north and south gates.

They built a royal chapel and redesigned the gardens.

But if the castle was starting to look prettier, it still had a dark side.

These new kings of Scotland also used Stirling as a place to do their dirty work.

The early Stuarts were a brutal, violent mob.

James I had several of his cousins executed outside these castle walls.

James II stabbed the Earl of Douglas to death and threw his body out of one of those windows.

And James III was so feckless, lazy and irresponsible, his own son was implicated in his death at the Battle of Sauchieburn.

That son was James IV.

James has gone down in history as Scotland's first true Renaissance king.

He was pious, well-read, charming, creative and spoke at least eight languages.

He was the first Stuart more interested in art and learning than in having his relatives murdered.

All the same, he kept some pretty peculiar company.

And under his rule, Stirling Castle hosted some of Europe's most extraordinary and eccentric characters.

James' reign might have begun in rebellion and intrigue, but it soon blossomed as he brought the best of the European Renaissance to Scotland.

He built the Great Hall here at Stirling, filled it with artists, poets, composers, scientists, doctors, diplomats, mistresses, and best of all, his own personal alchemist.

The goal of the alchemist was simple, to discover the mythical fifth element, or quintessence, and turn base metals into gold.

James' alchemist was a man called John Damian, who came from Europe to Scotland claiming to be a doctor.

The records describe him as the French leech, because he used leeches to bleed people in surgical procedures.

The problem was he wasn't very good at it.

And the records say, "In leech craft, he was homicide."

So he reinvented himself as an alchemist and persuaded James to pay for his furnaces here at Stirling Castle.

And very clearly, alchemy didn't come cheap.

Royal account books from the time give us a remarkable insight into the workings of Damian's laboratory.

We start with his clothes.

He has a long damask gown lined with lambskin, scarlet hose, velvet breeches, a cape and a hat.

In other words, he looked like a wizard.

But it's his list of ingredients which are great, coal and wood for his furnaces, tin, silver, salt.

Aqua vitae, which is a famous Scottish chemical compound better known as whiskey, and gold coins, obviously, to get the potion started.

Manuscripts of the period say he needed a quantity of good wine which would be distilled several times over furnaces.

So basically, he's making very strong, pure alcohol which would bring back the spring of youth and put the king and John Damian in a state of great highness of glorification.

The records also show Damian winning money from the king playing cards and dice.

I reckon he was a bit of a hustler.

(CLANKING) But he was a showman, too.

Damian kept the court entertained with his grand, public science experiments.

(SIZZLING) The most famous, and ridiculous, of all of them was quite literally launched on the castle walls.

The story goes, and I stress "story,"uh, that in September 1507, he announced to James IV's court that he would fly from Stirling Castle to France.

-JONES: To France?

-To France.

-That's quite a flight.

-It's a fair old distance.

But he was prepared.

He had wings made, made out of feathers, a "featherim" as it was known in Scots.

Of course, when he leaps away, he doesn't go out the way, he goes down the way.

But he is fortunate because he lands in a midden and has a soft landing.

JONES: He landed in a midden.

What's a midden?

Ah, a midden, another good Scots word.

A midden is essentially a rubbish dump, all the effluence from the castle, all the garbage from the kitchen, all gets thrown over the walls into the midden, the dump.

And that is what John Damian is said to have landed in.

-Soft, at least.

-A soft landing and ensured his survival.

(JONES LAUGHS) JONES: Although James IV was happy to indulge men like Damian, he also put Stirling Castle to good political use.

Perhaps James' smartest move was to secure an alliance with England by marrying Margaret Tudor, daughter of Henry VII and sister of Henry VIII.

She came north in 1503 with lands, a large dowry and the promise of perpetual peace.

But what no one could have known was that within three generations, this marriage would put a Scottish Stuart king on the throne of England.

Margaret gave birth to at least one of her six children at Stirling Castle.

And in 1513, after James IV was killed fighting the English at the Battle of Flodden, Margaret's 17-month-old son was crowned King James V in the royal chapel.

When James V grew up, he continued to develop the castle in rather unusual style.

To the left of the gatehouse, and forming the south side of the Inner Close, is the royal palace.

It's one of the most architecturally impressive buildings in all of Scotland.

In fact, it wouldn't look out of place in Versailles.

And there's a reason for that.

James V's second wife was Mary of Guise, a Frenchwoman who had turned down the chance to be Henry VIII's fourth wife saying, "I may be large of body, but my neck is small."

Together with James, Mary created this royal palace.

It's a beacon of French culture in the middle of Scotland.

And even today, it's one of the finest Renaissance buildings in Britain.

Inside, the palace is divided into two opulent apartments with their own bedchambers and reception rooms, one for the King and another for the Queen.

Most striking of all, though, is the ceiling of the King's Chamber, which is decorated with carved oak portraits known as the Stirling Heads.

They depict mythical figures, ancient emperors and Scottish royals.

And as the Stuarts would demonstrate, there was no shortage of those.

Scottish kings had a terrible habit of dying young and leaving children as their heirs.

James IV was 15 years old when he inherited his crown.

James V was only 16 months.

And when James V died, he left a six-day-old daughter as his heir, a little girl who would grow up one day to be known as Mary Queen of Scots.

From the minute she was born, Mary was one of the most divisive characters in all of British history.

She was talented, attractive, bright and doomed.

Her life story is one of history's greatest romantic tragedies.

And it began at Stirling Castle.

Mary was crowned here at Stirling when she was just nine months old, but in England, Henry VIII already had his eye on her, planning to marry her to his son and create a dynastic union between the two countries.

Mary's mother, Mary of Guise, was bitterly opposed to an English marriage for her daughter.

She knew it would break a 300-year-old alliance between Scotland and her native France.

But locking the princess away in castles like Stirling, so she couldn't be seized and taken to England, only made Henry VIII angry.

He ordered a series of brutal military raids on Scotland to bully them into releasing the princess.

It was known as the "Rough Wooing."

For her safety, Mary was shepherded to France when she was five.

She wouldn't be back for 13 years.

By then, both Henry VIII and his son were dead.

And Mary had married the King of France.

But in August 1561, she returned to the land of her birth.

Why did Mary come home?

Well, in 1560, her husband had died and she'd been sidelined from French politics.

But more importantly, two years earlier, Mary's cousin Elizabeth had become Queen of England.

And this was Mary's big chance.

She had Tudor blood in her veins, through her grandmother, Margaret.

She'd been Queen of France.

She was still Queen of Scots.

Now she wanted to be the lawful heir to Elizabeth's English crown, too.

Mary was ambitious, and she had plenty of supporters.

For many English Catholics, Elizabeth was the bastard Protestant heretic daughter of Anne Boleyn.

And Mary was the rightful Queen of England.

So at 18, Mary was returning to Stirling, to Scotland, and to her destiny.

Elizabeth wasn't entirely thrilled.

She refused to recognize Mary or anyone else as her successor.

And soon, Mary had problems of her own, back in Scotland.

In 1565, Mary married her cousin, Henry Stuart, Lord Darnley.

He was a violent, drunken troublemaker, who arranged for Mary's private secretary to be stabbed to death in front of her.

But Darnley also got Mary pregnant.

The Stuart dynasty would continue into another generation.

When Mary had her child, it was a boy, a male heir.

Obviously, they called him James and had him baptized here at Stirling.

There was feasting, bonfires and fireworks across Scotland, but there were problems, too.

The child's godmother was Elizabeth I of England, but her representatives stayed outside the chapel to protest the Catholic ceremony.

As an adult, Mary's son would unite the whole of Britain under his rule.

But this baby Stuart had the worst possible start in life.

Both of his parents would soon be gone.

One of them to prison and the other murdered.

James VI of Scotland grew up in the lavish surroundings of Stirling Castle.

But he had two big problems, his parents.

His father, Lord Darnley had refused to attend his son James' christening in Stirling's royal chapel in December 1566.

Soon afterwards, he contracted syphilis and left the castle.

He went to stay in a house on the outskirts of Edinburgh.

Weeks later, he was dead.

The house he was staying in was blown up with gunpowder and Darnley's naked body was found in the garden, the grim scene depicted in this contemporary picture.

Though there were no signs of violence on Darnley's corpse, the finger of blame pointed squarely towards men at the Queen's court.

The chief suspects were Mary's loyal circle of lords including the Earl of Bothwell who was reputed to be her lover.

Bothwell was acquitted, but within three months Mary had married him.

Placards in the street depicted Mary as a mermaid, the symbol of a prostitute.

She was forced to abdicate, leaving her one-year-old son as King James VI of Scotland.

Less than a week after Mary Queen of Scots abdicated, James was crowned in Stirling parish church.

He was 13 months old.

The following year Mary fled Scotland, hounded out by her political enemies.

She headed south and threw herself on the mercy of her cousin, Elizabeth I of England.

But instead of helping Mary return to rule Scotland, Elizabeth put her in prison.

She stayed there for nearly 20 years before being beheaded for plotting against the English queen in 1587.

James VI didn't have the best start in life.

After all, his father had been murdered, his mother had been branded a whore and forced to abdicate.

In fact, his whole family history was of betrayal, backstabbing and murder.

You have to wonder, what chance did this poor kid have?

The education James received at Stirling was a matter of massive political importance.

His attitudes towards issues like religious reform were going to shape Scotland's future.

Unlike his Catholic mother, James was brought up as a member of the Protestant Church of Scotland.

He was educated by tutors appointed by the Privy Council.

They included the highly respected humanist scholar George Buchanan.

This is the schoolroom where James VI received his lessons from his tutor George Buchanan.

James was a very good pupil.

He learned history, rhetoric, mathematics, languages and military strategy.

Most importantly, Buchanan tried to teach James about his duties and responsibilities as a constitutional monarch.

And he wasn't afraid to beat the lessons into the young king either.

James VI's education would set him up.

This was the king who would sponsor the King James Bible, and write his own treatises on kingship.

But it was his bloodline that really changed his life.

Elizabeth I had spent much of her reign trying to keep her cousin Mary Queen of Scots away from her throne.

But when Elizabeth died in 1603, there was only one heir, Mary's son James VI of Scotland, who now became James I of England and Ireland as well.

He left Stirling, and only returned to Scotland once in his lifetime.

When James left for England to take up his new crown, he took his family with him.

Stirling's use as a royal residence declined.

It was no longer a thriving palace filled with alchemists' smoke or the voices of young princes in the schoolroom.

And 150 years later, Stirling was in a very sorry state.

The great Scottish poet Robbie Burns came to Stirling in 1787.

And he saw the terrible state the castle was in, with the palace roof collapsed.

Now, Burns used to carry a diamond-tipped pen which he'd use to scratch messages and verse into glass.

And while he was staying here he scratched a poem into the window, and it said, "Here Stuarts once in triumph reigned "And laws for Scotland's weal ordained "But now "unroofed "their palace stands "Their scepter swayed by other hands."

But that didn't go down very well with the locals, so later Burns came back and he smashed the pane of glass.

But if Burns came here today, he'd probably be pleasantly surprised.

Stirling doesn't just have a roof, it's been completely restored to the glory of its golden age under the Stuarts.

900 years after its foundation, Stirling Castle remains a unique monument to the history of the two kingdoms it has both divided and united.

With names like William Wallace, Mary Queen of Scots and Robert the Bruce, Stirling certainly is a very Scottish castle, but it's a very British castle as well.

This is the palace that educated James VI, the first man ever to claim the crowns of England, Scotland and Ireland.

And best of all, it's a living castle, not a ruin.

As solid and indestructible as the rocky crag it's perched on.