Through the presence of his empress wife Theodora and two generals, namely Belisarius and Narses, the Africa and Italy was recovered from Vandals and Ostrogoths respectively. Success was not on his side in struggle against Persians, and avoiding attacks of the Bulgars and Slavs. The greatest achievement of Justinian was the Corpus Juris Civilis, which refers to the codification of the Roman law. It was also during Justinian time that many public works took place, and one structure worth mentioning due to its enormous and meticulous construction is the Church of Hagia Sophia. It was designed by the imperial architects of Justinian, Anthemius of Tralles and Isidorus of Miletus, and was built from 532 to 537. It was constructed by Constantius II in 360, after the declaration of Byzantium as the capital of the Roman Empire. Hagia Sophia was burned in 404 and was reconstructed in 415 by Theodisius II, but was burned again in 532. It collapsed in 558 due to earthquake and was rebuilt again in 563.
Constantinople was attacked by the Persians, Arabs, Russians and Bulgars from 6th to 13th century, and members of the fourth crusade in the succeeding years due to its strategic location in terms of transport and trade among continents.