The Vatican Obelisk, which stands in Piazza San Pietro, is the only one of the thirteen Egyptian obelisks in Rome to have remained standing following the fall of the ancient Roman empire in the west.
The obelisk has no hieroglyphs, which makes it difficult to assess its exact age. It was brought to Rome by the Emperor Caligula (r. 37-41 CE) and set up on the spina of the circus he was building on Mons Vaticanus. The circus was completed by Caligula's successor, Nero, and bore his name (Circus Neronianus).
For centuries the obelisk stood on the south side of St. Peter's Basilica before it was moved, in 1586, to its present position. Pope Sixtus V (r. 1585-90) entrusted the task to the architect and engineer, Domenico Fontana (1543-1607). The obelisk, which is 25 metres high and weighs roughly 330 tons, was erected (with the aid of 900 men,140 horses and 44 winches) on September 10th.
The Vatican Obelisk was originally crowned with a bronze globe, which was believed to contain the ashes of Julius Caesar. However, when the globe was opened it was found to be empty. It is now on display in the Museo dei Conservatori.