You will find the ruins of ancient Rome throughout the city. One reason is that re-use has preserved many of the magnificent structures of Imperial Rome. The Temple of Hadrian is a fascinating example of this. Although the structure as a whole no longer stands, you can easily see the wonder of the building, for the large columns and the entablature survive in a modern building. The remaining wall of the Temple of Hadrian sits in its own Piazza, so there is plenty of time t

The Castel Sant'Angelo, or Mausoleum of Hadrian, is a large, circular structure on the Tiber River, visible from St. Peter's Basilica. Originally Hadrian's mausoleum, its solid construction made it an ideal papal fortress, connected by a visible passage to St. Peter's. It also served as a prison, holding Caterina Sforza and the fictional Mario Cavaradossi from Puccini's Tosca.