- [Narrator] Many foods in Chicago are neighborhood dependent.

However, there is one food that seems to touch everyone everywhere, pizza.

(funky jazz music) - Typically, when you walk through the front door of a pizzeria, you're gonna smell the scent of the baking bread.

You're gonna smell oregano.

There's fennel a lot of times in the sausage.

And when we talk about pizza in Chicago, the default is sausage.

- We're a sausage town, just knobs of sausage baked in.

- [Narrator] Chicago's favorite go-to is a sausage pizza with a very thin crust.

- After World War II, you have this really thin tavern-style pizza come up.

- Why?

Because if you give your guests something salty to eat, they wanna order more beers and they're really just making money off the beers, frankly, not the food.

- [Narrator] It's known as tavern style pizza because it was served as a free appetizer in taverns, places like Vito and Nick's, owned by the Baracco family, - These are thin and crispy pizzas, very thin, cut into little squares, passed around the bar, so you can put a square on a cocktail napkin.

You don't need a plate, you don't need a knife and fork.

- It is by far the most entertaining and dynamic way to eat a pizza.

It's also the most crowd-pleasing.

I'm a middle piece guy.

I'll go right in there and like hot tub it, right from the center.

Grab that squishy middle piece and (blows raspberry).

Right, got those corners.

Those are the little snacks.

Everybody comes from the basement.

You take one of those four corners, usually pop 'em in.

- [Narrator] While tavern style is the favorite of locals, it's another type of Chicago pizza that gets all the attention and draws in the tourists, deep dish.

- I think people all over the country think we're like every Friday, we're getting down with like a deep dish for the family.

That's not the case.

- [Narrator] The sheer size of the high-crusted pie means diners have to sit down and pull out their knives and forks and the city overflows with options.

- Who has the best deep dish?

Is it Pequod's?

Oh, but they suck at delivery so you can't get 'em.

And then what makes Lou Malnati's and who likes the cornmeal?

And I don't like this tomato sauce at this one.

Everybody has their opinion.

- [Narrator] Deep dish is a 100% Chicago creation and its creator, Ric Riccardo, was a free-spirited Italian artist who opened a successful bar near the city's bohemian neighborhood.

- Ric Riccardo was kind of a bon vivant.

His exploits are written about in the newspaper.

- [Narrator] In 1942, Riccardo had a new wife and a new baby and had just moved them into an aging mansion close to his bar.

- [Monica] He lived at Ohio and Wabash.

He was on the third floor.

- [Historian] And then downstairs is the Pelican Club.

He wants to make a place with no music basically because he wants to be able to sleep at night.

- [Monica] And he says, "Darn it, I'm gonna buy that tavern so that it's nice and quiet.

I'm gonna have a nice family-style restaurant."

- [Narrator] The Pelican Club already had pizza ovens and Riccardo believed Chicagoans would be excited to try a new kind of pizza, one unlike anyone had seen before.

- [Historian] He finds these pans in the back, these cake pans, and they start pressing the dough out into the bottom of the pan.

You press it up along the wall a little bit.

- And then you have your cheese, and then you have your sauce, which was different from a lot of pizzas where the cheese was the the top bubbly layer.

- [Narrator] After a year of perfecting the recipe, he opened the doors of Riccardo's Pizzeria and deep dish became an immediate sensation.

- These deep dish pizzas become popular.

They would have pictures of Riccardo with these celebrities holding up slices of these deep dish pizzas.

- [Narrator] Eventually, Chicago would have more than 100 deep dish pizzerias, many opened by former cooks at Riccardo's, which came to be known as Pizzeria Uno.

But Riccardo's role as the sole creator of the pizza now synonymous with Chicago was nearly erased after his death.

Pizzeria Uno's new owner, Riccardo's business partner, Ike Sewell, took credit.

- There's a plaque in front of Uno's that says, "This is where Ike Sewell created deep dish pizza, 1943."

That is not true.

Ric Riccardo created deep dish pizza.

Now that we have the information, let's tell the truth.

(horn blasting) ♪ Oh say, can we eat ♪ - [Narrator] Few dishes spark such Chicago pride as our deep dish pizza.

♪ Deep dish, proudly inhaled ♪ - Deep dish pizza is quite good.

(glass shattering) - [Narrator] But it does have its critics.

- Are no doubt taking personal offense to the "Daily Show" host John Stewart's rant against our deep dish pizza.

- [TV Host] John Stewart trashing our Chicago style pizzas.

- Lemme tell you something.

this is not pizza.

This is tomato soup in a bread bowl.

- [Narrator] Love it or hate it, it's all Chicago.

- I had some recently, still a good pie.

So good.