The Western Renaissance had been founded on the idea

of rebuilding the ruins of the classical pagan past

and re-consecrating them for a new Christian age.

The supreme test would be St Peter's.

The original basilica built by Constantine in the fourth century

was, by 1500, in danger of collapse.

In 1505, Pope Julius II shocked Rome

by deciding to demolish the old basilica.

The visionary architect Donato Bromante won the competition

to build its successor.

He got the job because a small,

perfect building caught the Pope's eye.

This little gem is really a glimpse inside the Renaissance mind,

in particular, into Donato Bromante's mind.

It's a freestanding shrine to St Peter

in the cloister of the church of San Pietro in Montorio,

the place where St Peter himself was said

to have been crucified upside down.

Let's think about what the word Renaissance means.

It means a rebirth.

And what was being reborn was classical antiquity.

Bromante walked around Rome making very careful

scholarly notes of what he saw.

What he saw were pagan temples.

So, what we have here is the perfect classical form

of one of those ruined Roman temples.

A dome, sitting on a drum,

with a colonnaded encirclement outside.

And, as such, what it does is take those perfect forms,

the hemisphere and wheeling circle,

the revolution of the planets,

like a great cosmic timepiece, and says,

this, harmoniously, is how the new sacred art is going to be.

There's something else on Bromante's mind, as well.

This is really a miniature size, doll's house prototype

for what he will want to happen to St Peter's itself.