Although much restored, San Giovanni Evangelista is one of the oldest monuments in Ravenna, dating from c.426-30 AD. Its chief attractions are its fine 5th-century architecture and 13th-century mosaics depicting the Crusades.San Giovanni Evangelista was commissioned by the empress Galla Placidia in fulfillment of a vow she made during a storm in 424 while sailing from Constantinople to Ravenna. She came to Ravenna to assume the government of the western Roman empire on behalf of her young son, Emperor Valentinian III.In about 600 AD, the basilica was expanded by incorporating the narthex into the church and the interior was redecorated under Archbishop Marinianus (c.598-606). A mosaic fragment containing part of his name was found beneath the church. Further renovations were done throughout the Middle Ages and in the Baroque period.In 1944, Allied bombs intended for the nearby train station completely destroyed the west facade and first four bays of the nave and badly damaged the apse and side aisles. It was rebuilt to its original form after the war and still contains many original elements. Entrance is through a 14th-century Gothic marble portal, which leads into a reconstructed brick atrium. The west facade features a very tall arched porch, which was completely rebuilt after World War II. The square campanile (10th to 14th centuries) stands 139 feet high and contains two bells cast in 1208. A significant amount of mosaics from the church do survive from the pavement added in 1213 under Abbot Guglielmo. Vault of a chapel in the left aisle, with fragments of beautiful 14th-century frescoe depicting the Four Evangelists with their symbols and four Doctors of the Church. Now framed in sections and mounted on the side walls, the naive mosaics depict a range of fascinating subjects including mythical animals, scenes from medieval novels (such as a fox's funeral), and, most importantly, scenes from the Fourth Crusade (1204) including the taking of Zara and Constantinople. Fragment of Romanesque mosaic floor (1213 AD) in San Giovanni Evangelista, Ravenna, depicting a blonde mermaid (or siren) with a thorny double tail. Fragment of Romanesque mosaic floor (1213 AD) in San Giovanni Evangelista, Ravenna, showing the fall of Constantinople to the Crusaders in 1204. Fragment of Romanesque mosaic floor (1213 AD) , depicting Crusaders of the Fourth Crusade (1199-1204).