Circus of Nero
Coordinates: 41°54′5.82″N 12°27′14.94″E / 41.9016167°N 12.4541500°E
The Circus of Nero or Circus of Caligula was a circus in ancient Rome, located mostly in the present-day Vatican City.
The accompanying plan shows an early interpretation of the relative locations of the circus and the medieval and current Basilicas of St. Peter. The plan also suggests the dimensions of the circus relative to the Basilicas. A more modern interpretation differs in various respects: it maintains the central obelisk in the same position relative to the Basilicas, as in the accompanying plan, but rotates the entire circus about the obelisk, in a clockwise direction, about 170 degrees, so that the starting gates of the circus are now towards the east, and closer to the centre of Rome. The more modern interpretation also shows the circus as being much longer, relative to its width as compared to the early interpretation. See plan: "Outline of St. Peter's, Old St. Peter's, and Circus of Nero".
In both interpretations the circus building is centred on the obelisk; is aligned on a similar east-west line to that of the Basilicas; and lies to the south of the axis of the current Basilica (to the left as you look at the western front from the piazza). The major differences are in the relocation of the starting gates to the eastern end, and the change in proportions of the circus itself.
It was begun by Caligula on the property of his mother Agrippina on the Ager Vaticanus (today's rione of Borgo), and finished by Claudius.
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