The
Ager Vaticanus, the alluvial plain outside the city walls on the west bank of the
Tiber, was developed at the end of the first century BC, allowing patrician families to construct luxurious private residences (
Horti). The
Horti Agrippinae villa-estate belonged to
Agrippina the Elder and was inherited by her son
Caligula (r. 31–41 AD). He was a chariot-racing enthusiast and began construction of the circus which was completed by
Claudius (r. 41-54 AD). The privately owned
circus and
Horti were then inherited by
Nero who made the circus public so he could invite them to cheer him on. He also used both of these to lodge Romans made homeless by the great fire of 64. The circus was used in 65 to carry out mass executions of the Christians accused as scapegoats of the fire itself. Because of this the area beyond the Tiber north of
Trastevere was known as "Nero's meadows" until the end of the Middle Ages. The circus was also the site of St. Peter's martyrdom. The circus was abandoned by the middle of the second century AD, when the area was partitioned and given in concession to private individuals for the construction of tombs in the
necropolis.
Old St. Peter's Basilica was erected by Constantine over the site using some of the existing structure of the Circus of Nero. The basilica was sited so that its
apse was centred on Peter's tomb (now beneath the high altar of the current
St Peter's Basilica). Most of the ruins of the Circus survived until 1450, when they were finally destroyed (along with the Old St. Peter's Basilica) for the construction of the new St. Peter's Basilica. ==Place of martyrdom==