Blachernae (Greek: Βλαχέρναι) was a suburb in the northwestern section of Constantinople, the capital city of the Byzantine Empire. It is the site of a water source and a number of prominent churches were built there, most notably the great Church of St. Mary of Blachernae (Panagia Blacherniotissa), built by Empress Pulcheria in circa 450, expanded by Emperor Leo I (r. 457–474) and renovated by Emperor Justinian I (r.