Looking like a mere wall, inside is a secret passage between Vatican City and the Castel Sant'Angelo, where Popes could escape during bad times. Here the picture shows the dome of Saint Peters with the Passetto di Borgo heading toward the Castel Sant'Angelo. Find out more about Castel Sant'Angelo from Europe Travel.
The passetto is one of the Rome and Vatican sites in Angels and Demons, the movie based on Dan Brown's popular book, Angels and Demons.
