Baroque Heart of the Campus Martius

Campo de' Fiori

A working market square since the 15th century, with fresh produce, flowers, and the brooding statue of Giordano Bruno at its center.

You're standing in a square whose name means field of flowers, a memory of the meadow that was here before the city paved it over in 1456. For most of its life this has been a market, not a monument. The streets leading into it are named for the trades that once lined them: crossbow makers, coffer makers, hat makers. The market stalls around you sell seasonal produce, cut flowers, spices.

If you're here before nine in the morning, you're seeing it at its best: locals doing their weekly shop, vendors calling out prices, the espresso machine at the corner bar running nonstop. Later in the day the tourist stalls multiply and the square shifts character, but right now this is still a neighborhood. Now look at the hooded bronze figure in the center. That's Giordano Bruno, the philosopher and former Dominican friar who was burned alive on this exact spot on February 17, 1600.

His crime was insisting that the universe was infinite and contained countless other worlds, and he refused to recant. The statue was put up in 1889 over furious protest from the Vatican, and it faces deliberately toward it. The inscription reads: 'To Bruno, from the century he foresaw, here where the pyre burned.' For a market square, this place carries an unusual weight.

Piazza Navona

Rome's most theatrical square, built over Domitian's stadium, with Bernini's Fountain of the Four Rivers at its heart.

You're standing inside a stadium. That long oval shape isn't a Baroque invention; it's the footprint of the Stadium of Domitian, built around 80 AD to host foot races and wrestling matches for thirty thousand spectators. For centuries after the empire fell, Romans built houses into the old stone seating, and the arena became a muddy piazza. The shape survived.

In the seventeenth century, Pope Innocent X Pamphili turned it into the square you see now. His family palace faces you on the left, and the church of Sant'Agnese in Agone, designed by Borromini, curves on your right. But the star is dead center: Bernini's Fountain of the Four Rivers, unveiled in 1651. Four river gods sprawl around a jagged travertine rock that supports an Egyptian obelisk.

The Ganges carries an oar, the Nile's head is veiled because its source was then unknown, the Danube touches the papal coat of arms, and the Río de la Plata throws up a hand in alarm at the sight of a serpent. The dove on top is the Pamphili family emblem. The whole thing is a theater of water and stone, and Bernini meant for you to walk all the way around it. At the southern end, the Fountain of the Moor was carved by Giacomo della Porta in 1575, with Bernini adding the central figure of a Moor wrestling a dolphin a century later.

At the northern end, the Fountain of Neptune balances it out. Take a lap.

Pantheon

The largest unreinforced concrete dome on earth, standing for nineteen centuries with an open oculus to the sky.

The building in front of you has been standing for more than nineteen hundred years, and its dome is still the largest unreinforced concrete dome on the planet. Not the largest in antiquity, not one of the largest: the largest, period. Forty-three point three meters across, and forty-three point three meters high. A perfect sphere would fit inside.

The secret is in the concrete. The aggregate changes as the dome rises. Heavy travertine chips at the base, then tufa and broken brick in the middle, and at the crown, around the oculus, lightweight volcanic pumice. Each layer is thinner and lighter than the one below it.

The oculus itself, almost nine meters wide, does more than let in rain and light; it relieves the stress at the dome's weakest point and acts as a compression ring, holding the whole structure together. The inscription across the portico, M AGRIPPA L F COS TERTIVM FECIT, credits Marcus Agrippa, who built the first temple here in 27 BC. That one burned. The emperor Hadrian rebuilt it around 126 AD and modestly kept Agrippa's name.

Since 609 it has been a church, Santa Maria ad Martyres, which is why it survived when so many ancient Roman buildings were stripped for stone. The artist Raphael is buried here, in a tomb near the altar. Entry requires a ticket. Join the queue that snakes across the portico.

Once inside, stand under the oculus and look up. On a rainy day, the floor is wet in a perfect circle. On a clear day, a column of light moves across the coffered ceiling like a slow sundial. The Romans built this, and almost two thousand years later, no one has built a bigger unreinforced concrete dome.

Michelangelo, designing St. Peter's, came ninety centimeters short.