Pompey's Pillar is a Roman triumphal column in Alexandria, Egypt, and the largest of its type constructed outside of the imperial capitals of Rome and Constantinople. The only known free-standing column in Roman Egypt which was not composed of drums, it is one of the largest ancient monoliths and one of the largest monolithic columns ever erected.
The monolithic column shaft measures 20.46 m in height with a diameter of 2.71 m at its base. The weight of the single piece of red Aswan granite is estimated at 285 t. The column is 26.85 m high including its base and capital. Other authors give slightly deviating dimensions.
Erroneously dated to the time of Pompey, the Corinthian column was actually built in 297 AD, commemorating the victory of Roman emperor Diocletian over an Alexandrinian revolt.