[heavy rain hissing] [thunder rumbles] - [Narrator] This isn't a new video game.

It's a research project.

[thunder rumbles] That's St Paul's Cathedral in London.

- [John] Visually, it was the dominant image on the horizon.

- [Narrator] It is Easter Sunday, March 28th, 1624.

- So it became the center of cultural life as well as a religious life and of social life for the entire city.

- [Narrator] Modeling the past provides a new way to access the past.

- But I don't think you can say that St Paul's Cathedral is just a church.

It was the center of life, of public life, of religious life in London.

- [Narrator] And a team of scholars at North Carolina State University believes St Paul's Cathedral is the best portal to provide a glimpse of daily life and understand London in the 1620s.

- So I think we were really curious to understand what that looked like in the 17th century, what it sounded like.

Imagine even what it smelled like when you see some of the renderings.

You feel like you're there.

We want to understand the air quality.

We want to understand the light quality.

How the building changed because of those things, how it weathered and got a patina over time.

And so the model allows us to do that.

- [Narrator] They recreated the sight and sounds of the cathedral and the surrounding neighborhood into a 3D model that you can interact with on a computer.

Call it architectural archeology.

- [David] So archeological records tell us where the old cathedral was.

So we had a great degree of certainty about its footprint.

- [Narrator] Researchers draw on written accounts, drawings, and paintings.

- There is indeed an enormous amount of visual material and archeological evidence that survives from this period.

So we know, generally, what the place looked like, and we know how big everything was and where things were located.

So we have the elements that we need to build a model of it.

Here's a chance to experience what reformed worship was like in London, in this cathedral.

- There are many different iterations of all of these columns.

Like what you see here was not the first thing that was built, right?

It's sort of a build, fact check, rebuild, fact check, build again.

And then, you know, when it gets to the coloring portion for the renderings that, you know, you see on the website, it's paint, render, fact check, repaint, render, fact check.

- [Narrator] And it turns out weather records were carefully kept during the time.

That's important because cathedrals were designed to take advantage of sunlight and shadows.

- Behind us is the interior model.

And the most important thing with that is, I don't know if you've been in cathedrals in Europe, but you know the grand scale and the filtering of light coming through the windows.

It's very important to get that atmosphere right, to making it feel correct.

- So you don't just say, all right, sun's up here.

Boom, blast of light coming down.

You're factoring all that stuff in.

- No, it's about, you know, is the sun going to be right here, or is it gonna be right here?

Because between the two of them, you'll get different reflections and seeing, you know, an image where everything is mostly right.

It's about the suspense of disbelief.

So orienting this proper north south and getting the actual sun angles and being true to life, sun heights and doing like atmospheric modeling, it put introducing smoke and smog to those calculations.

You know, the computer program is smart enough to figure all that out.

I just have to tweak and tweak and tweak.

- [Narrator] Researchers even hired an international collection of singers and actors to recreate services from Easter Sunday, March 28th, 1624 as well as an ordinary weekday service in 1625.

- Like, it's amazing that we're able to go back in time and kind of figure out what things looked like back then, and be able to kind of see how people lived and how people built buildings and how people used them and how like the choir sounded in this building back then.

[grand choir singing echoes] - [Narrator] So why do all of this?

Well, it's important to remember the church's role in 17th century England.

The king was the head of the country, and the head of the Church of England.

People were legally obligated to attend church.

- The Church of England was a state church.

The monarch was officially the supreme governor of the Church of England.

The sermons in the cathedral and in Paul's churchyard were often sermons that addressed political issues.

- [Narrator] In short, the church is a window to the art, culture, literature and broader history of the times.

- We're able to pull all that data together into a powerful visual realization of what it looked like.

We can not simply know as an abstract idea, but in fact experience what that was like, and how people were formed, and how this inshaped and informed their lives.