Vatican Aerial View

St. Peter’s and the Vatican from the air, circa 1925. The Via della Conciliazione, the wide road leading into St. Peter’s today, had not yet been cleared; that began in 1936.

Note the wall behind St. Peter’s on which telescope domes can be seen. This fortification has walls a good four and a half meters thick and is one of the few bastions still standing of the fortification which was called “leonina”, because Saint Leo IV had it built in 840 as a defense against the Saracen invasions.

The numbered spots on this wall indicate: 1. the Leonine Tower with the telescope dome for the 1891 Carte du Ciel telescope; 2. the semi-circular “Half-tower” housing a small (10 cm aperture) Merz refractor, moved from the Tower of the Winds; 3. the “American Bridge” across the part of the wall that had collapsed in 1854; 4. the 8.8 m dome housing the 1909 Merz refractor on the Tower or St. John; 5. the Heliograph; 6. the Tower of the Winds, where the offices of the Vatican Observatory were located.