Piazza Navona historical timeline

A Greek-style athletics stadium that was never demolished — only built on top of, lived in, flooded for fun, and finally paved over.

Chronology

1. c. AD 80–86 — Domitian builds a stadium on the Campus Martius. Turismo Roma dates it to 86 AD; the reference work's Piazza Navona article says 80 AD, while its Stadium of Domitian article gives commissioned around AD 80 and dedicated in AD 86. It was Rome's first permanent venue for competitive athletics, built for the Capitoline Games. Structural impact: a Greek-plan arena of roughly 275 by 106 metres seating about 30,000, in brick and concrete clad in marble, with facades resembling the Colosseum's. What you see today: the shape of the square, which is the shape of the track.
2. Antiquity — the stadium is used almost entirely for athletic contests, and the Latinised Greek in agones, the place of the competitions, gives it the name Circus Agonalis. Structural impact: none. What you see today: the word Navona itself — Turismo Roma derives it from Agones, Latin for games.
3. After the fall of the Western Empire — the stadium falls into ruin and is quarried for building materials. Structural impact: the marble and much of the fabric go; the foundations stay, because nobody digs up what they are standing on. What you see today: the remains 5 to 6 metres down, visible under a building in Piazza di Tor Sanguigna and in the crypt of Sant'Agnese.
4. 1450 — the church later known as Nostra Signora del Sacro Cuore, then San Giacomo degli Spagnoli, is erected for the Jubilee. Structural impact: the arena's edge becomes a street frontage. What you see today: the church facing Palazzo Pamphilj.
5. Late 15th century — the square is defined as a public space when the city market is transferred here from the Campidoglio. Structural impact: a ruin becomes a working piazza. What you see today: the reason it was worth decorating at all.
6. 1574–1575 — Giacomo della Porta builds both end fountains: the Fountain of Neptune at the north (1574) and the basin and four Tritons of the Fontana del Moro at the south (1575). Structural impact: the long axis acquires its two end-stops, sixty years before anything stands between them. What you see today: both basins — and one of them still waiting for its title figure.
7. 1644–1655 — the pontificate of Innocent X, whose family palace faces the piazza. The square is remade as Baroque architecture and art. Structural impact: a papal family rebuilds its own front yard. What you see today: essentially everything above ground.
8. 1651 — Bernini's Fontana dei Quattro Fiumi goes up at the centre, carrying the Obelisk of Domitian, brought in pieces from the Circus of Maxentius. Structural impact: the piazza gains a vertical, and the axis a middle. What you see today: the reef, the four rivers, the obelisk and the dove.
9. 1652–1866 — every Saturday and Sunday in August the square is flooded for the Pamphili family's celebrations. Turismo Roma notes the square then had a concave floor, which is what made it hold water, and that the flooding gave Romans relief from the heat. Structural impact: the paving is dished on purpose. What you see today: nothing — and that absence is the point; see 1800s below.
10. 1673 — Bernini adds the wrestling figure to the Fontana del Moro, ninety-eight years after della Porta's basin. Turismo Roma names it the Ethiopian; the reference work names it a Moor. Structural impact: the south fountain gets its subject. What you see today: the figure the fountain is named for.
11. 19th century — the pavement level is raised, and in 1866 the August festival is suppressed. Structural impact: the concave floor is flattened, so the square can no longer be flooded. What you see today: flat paving, and the end of a 214-year habit.
12. 1869 — the market moves out to nearby Campo de' Fiori. Structural impact: the piazza stops being commercial infrastructure. What you see today: a square given over to looking at, and the market still running at Campo de' Fiori.
13. 1878 — Antonio Della Bitta adds the statue of Neptune to della Porta's 1574 basin, to create a balance with the Fontana del Moro. Structural impact: the north fountain finally matches the south. What you see today: a Neptune 304 years younger than the fountain he stands in.
14. 1960 — Palazzo Pamphilj becomes the embassy of Brazil. Structural impact: the pope's family palace becomes diplomatic premises. What you see today: the one building on the square you cannot simply walk into.
15. 3 September 2011 — a vandal climbs into the Fontana del Moro with a large rock and decapitates several of the figures. Structural impact: restoration, and a sharper view of people in the fountains. What you see today: repaired sculpture, and why nobody is relaxed about you sitting on the rim.