“Pompey’s Pillar”, a Roman triumphal column, is one of the best-known ancient monuments still standing in Alexandria today. It is located on Alexandria’s ancient acropolis—a modest hill located adjacent to the city’s Arab cemetery—and was originally part of a temple colonnade. Including its pedestal, it is 30 m (99 ft) high; the shaft is of polished red granite, 2.7 m (8.9 ft) in diameter at the base, tapering to 2.4 m (7.9 ft) at the top. The shaft is 88 ft (27 m) high, and made out of a single piece of granite. Its volume is 132 m3 (4,662 cu ft) and weight approximately 396 tons. Pompey’s Pillar may have been erected using the same methods that were used to erect the ancient obelisks. The Romans had cranes but they were not strong enough to lift something this heavy. Roger Hopkins and Mark Lehrner conducted several obelisk erecting experiments including a successful attempt to erect a 25-ton obelisk in 1999. This followed two experiments to erect smaller obelisks and two failed attempts to erect a 25-ton obelisk.[51][52] The structure was plundered and demolished in the 4th century when a bishop decreed that Paganism must be eradicated. “Pompey’s Pillar” is a misnomer, as it has nothing to do with Pompey, having been erected in 293 for Diocletian, possibly in memory of the rebellion of Domitius Domitianus. Beneath the acropolis itself are the subterranean remains of the Serapeum, where the mysteries of the god Serapis were enacted, and whose carved wall niches are believed to have provided overflow storage space for the ancient Library. In more recent years, many ancient artifacts have been discovered from the surrounding sea, mostly pieces of old pottery.