Now located in the St. Peter’s Square, the Vatican Obelisk was brought from Heliopolis during the reign of Caligula and set up on the spina of the Circus of Gaius and Nero in Rome.
It is a monolith of red granite without hieroglyphs with a height of 25.36 meters. It has with dedications to Divus Augustus and Tiberius overlying partially erased inscriptions of Cornelius Gallus on opposite faces at the base of the shaft. It was standing the Forum Julium at Alexandria around 30 BC. It required a specially built ship to transport it from Egypt, which was later sunk to make the foundation of one of the breakwaters of the Claudian port at Portus Augusti and a lighthouse built on it.
Executions of Christians took place in the Circus of Gaius and Nero, during which time St. Peter was crucified. At the end of the century, the circus was abandoned and the Vatican hill turned into a necropolis. In the Middle Ages, the obelisk was still standing at the same place, then south of St. Peter's Basilica. A tradition soon arose that associated the obelisk and obelisk and its surroundings with the martyrdom of St. Peter, leading it to be called Pyramis Beati Petri (“the Pyramid of Blessed Peter”). A later medieval tradition regarded it as the funerary monument of Julius Caesar, whose ashes were supposed to be contained in a bronze orb on its top (now in the Capitoline Museums). In 1586 it was moved from its original position to the center of the piazza by Domenico Fontana at the behest of Pope Sixtus V.

See also Roman Monuments and Roman Obelisks