And, four centuries later, it’s still the largest church in the world.
So here’s a brief introduction to St Peter’s…
Because this is an immensely impressive building — it was and remains the world’s largest church by volume.
Others are taller, but none are so vast.
And, again, it has proportions beyond gargantuan.
The baldachin alone (a kind of ornate canopy, below) is 30 metres tall.
It stands on the site of an older church built by order of Constantine the Great and completed in 360 AD.
By the 16th century Constantine’s church was in a state of disrepair.
Why? He wanted a building of sufficient size and glory to house his own tomb — which he commissioned Michelangelo to sculpt.
But his monumental tomb was never finished.
Julius died in 1513 and Michelangelo completed it thirty years later, on a far smaller scale than originally intended.
This was seen as corruption by many — including Martin Luther — and it helped stir up the Protestant Reformation.
Famed architects like Bramante, Sangallo, della Porta, Peruzzi, and Maderno worked on it, along with architect-artists like Michelangelo, Raphael, and Bernini.
A torturous history of design and redesign.
The dome is Michelangelo’s, the façade is Maderno’s, the colonnades are Bernini’s, the apses are Raphael’s, and so on.
Its colossal dome is the highest in the world — this is as much Michelangelo’s masterpiece as David.
But you can’t see it, hidden behind Maderno’s massive façade — which is also inscribed with Pope Paul V Borghese’s Latin name.
The dome is smothered by the nave and the apses, making it look like a separate building entirely, squashed inside another.
But here the dome is more coherent — it feels like a logical conclusion to the rest of the building rather than a separate element merely attached to it.
Compare St Peter’s to a Gothic cathedral, like Cologne.
This is vertical rather than horizontal — everything soars upwards.
It’s hard to dispute the mastery of Bernini’s baldachin, his Chair of St Peter (below), or the technical quality and sheer impressiveness of the ornamentation.
But, for some, there’s simply too much gold — it can feel like an overwhelming display of wealth.
There are literally thousands of works of art within St Peter’s Basilica — it is an art gallery of its own.
Here, beneath the marble panelling, are the oldest parts of the whole church — they date back to the time of Constantine and even before.
Compare it to Medieval cathedrals at Amiens or Siena, two monuments of Gothic architecture.
Notice the differences of form and decoration between these and St Peter’s.
With Gothic architecture, meanwhile, masons had more creative freedom — every element was varied, as at (for example) the Ducal Palace in Venice.
Neoclassical is regulated, rational, and standardised — Gothic is free, assymetrical, and varied.
St Peter’s is a masterpiece of Renaissance-Baroque architecture, which is neoclassical and fundamentally opposed to Gothic.
The term Gothic was itself invented by Renaissance scholars as an insult to “barbaric” Medieval architecture.
It is monumental, imposing, and impressive — by design.
The impossibly thin piers at Amiens, meanwhile, give that cathedral a feeling of weightlessness.
Its windows were cleverly placed so that sunlight often falls as singular, almost heavenly rays onto the floor of the basilica.
Dramatic Baroque design at its finest.
St Peter’s may have its gold, but it has nothing like this:
It has also been immensely influential, shaping everything from the aforementioned St Paul’s to the Basilica of Our Lady of Peace in Yamoussoukro.
It is simultaneously the personal dream of Julius II, the physical embodiment of the Catholic Church’s response to the Reformation, religiously and artistically, and also the crowning achievement of Renaissance-Baroque architecture.
Unique.
