Piazza Navona keeps the exact shape of a racetrack: its long, rounded oval traces the lanes of Emperor Domitian's stadium, built for Greek athletic games around AD 86 and still buried a few metres below the paving. The name drifted from the Latin for those contests, in agone, into Navona. Market stalls and houses grew over the ruined seating until, in the 1600s, the Pamphilj pope Innocent X reshaped the space into a baroque showpiece, crowned by Bernini's Fountain of the Four Rivers, its Egyptian obelisk poised above four giant gods of the world's great rivers.
You enter and the piazza opens like a room without a roof, ringed by ochre facades and the curved front of Borromini's church of Sant'Agnese in Agone. There are three fountains in a line: Bernini's loud one in the middle, the Fountain of the Moor at the south end, and the Fountain of Neptune at the north. Portrait artists set up easels, café tables spill across the stone, and no cars intrude. In winter a Christmas toy market fills the square, and at dusk the travertine turns gold.