A recent issue of KMT magazine happens to have a really interesting article on the erecting of the obelisk in St. Peter's Square (Spring 2012, pages 37-51). Although the precise origin of the obelisk is not well understood—meaning to which Egyptian historical period it belonged or who commissioned it—Caligula had it erected in his favorite place, the Circus Maximus. It was there, nearby the obelisk, where Peter is said to have been crucified, upside-down on the cross.
That is why the obelisk interested the Vatican. Constantine razed the Circus Maximus and built the original Basilica of St. Peter on its foundations, with the obelisk still standing. However, the new basilica was begun in 1506 CE when the cornerstone was laid by Pope Julius II, by which time the old site at the Circus Maximus had fallen into ruins and the obelisk nearly forgotten. It was suggested in the early sixteenth century that the obelisk be moved to the new site. This fell under the sponsorship of Pope Sixtus V, who was very much interested in maintaining and glorifying Christiandom's architecture.
Domenico Fontana was the architect who won the contract to move and re-erect the obelisk. How he managed to do this is a fascinating tale and well told in the KMT article, but it's not the subject of this discussion. Simply put, the main reason the obelisk was moved to the new Basilica of St. Peter to become the centerpiece of the Square, is that the obelisk had witnessed the crucifixion and martyrdom of St. Peter. It was a natural fit.
The early Church delighted in claiming the monuments and icons of pagan religions for its own purposes. The obelisk in the Square may have been a pagan symbol, but note the ornamentation the Church added to the top to convert it to a Christian symbol. The Church certainly did not want to promote or glorify the ancient pagan religions of Egypt or Mesopotamia or Greece or Rome—it wanted to show its prowess in subverting them.
Edit: Monk, I'm a Moderator at Egyptian Dreams. How long have you been there?
Edited by kmt_sesh, 02 October 2012 - 06:46 PM.