The Roman Forum was located between the Palatine and Capitoline hills in Rome and was the central area around which ancient Roman civilization developed. St. Peter's Basilica in Vatican City occupies a unique position as one of the holiest sites of Christianity and the largest church, built over the burial site of St. Peter. The Mausoleum of Augustus was a large tomb built by the Roman Emperor Augustus in 28 BC on the Campus Martius in Rome, though now only ruins remain.