Nero's circus   

Standing at the centre of the track was an obelisk brought from Egypt—the very same obelisk that now occupies the centre of St Peter's Square. Tradition holds that the Apostle Peter was executed near the circus during Nero's persecution of Christians. Emperor Constantine later built the Old St Peter's Basilica on the site, directly over Peter's tomb. The circus was abandoned after the mid-second century, and its structures gradually vanished as the new basilica was developed. While many mistake the Circus Neronis for the Circus Maximus, Nero's circus was considerably smaller.