The Cathedral of the Protection of Most Holy Theotokos on the Moat are official names for a Russian Orthodox church in Red Square in Moscow. The church is also called the Cathedral of Vasily the Blessed, anglicized as Saint Basil's Cathedral. It was built from 1555–61 on orders from Ivan the Terrible and commemorates the capture of Kazan and Astrakhan.
St. Basil's marks the geometric center of Moscow (not to be confused with the geographic center, the Ivan the Great Bell Tower). It has been the hub of the city's growth since the 14th century and was the city's tallest building until the completion of the Ivan the Great Bell Tower in 1600.
Because the church has no analogues, in preceding, contemporary, or later architecture of Muscovy and Byzantine cultural tradition in general, the sources that inspired Barma and Postnik are disputed. Eugène Viollet-le-Duc rejected European roots for the cathedral; according to him, its corbel arches were Byzantine, and ultimately Asian. A modern "Asian" hypothesis considers the cathedral a recreation of Qolsharif Mosque, which was destroyed by Russian troops after the siege of Kazan.