The Cathedral of Vasily the Blessed (Russian: Собо́р Васи́лия Блаже́нного, tr. Sobór Vasíliya Blazhénnogo), commonly known as Saint Basil's Cathedral, is an Orthodox church in Red Square of Moscow, and is one of the most popular cultural symbols of Russia. The building, now a museum, is officially known as the Cathedral of the Intercession of the Most Holy Theotokos on the Moat, or Pokrovsky Cathedral. It was built from 1555 to 1561 on orders from Ivan the Terrible and commemorates the capture of Kazan and Astrakhan. It was the city's tallest building until the completion of the Ivan the Great Bell Tower in 1600.

The original building, known as Trinity Church and later Trinity Cathedral, contained eight chapels arranged around a ninth, central chapel dedicated to the Intercession; a tenth chapel was erected in 1588 over the grave of the venerated local saint Vasily (Basil). In the 16th and 17th centuries, the church, perceived (as with all churches in Byzantine Christianity) as the earthly symbol of the Heavenly City, was popularly known as the "Jerusalem" and served as an allegory of the Jerusalem Temple in the annual Palm Sunday parade attended by the Patriarch of Moscow and the Tsar.

The cathedral has nine domes (each one corresponding to a different church) and is shaped like the flame of a bonfire rising into the sky. Dmitry Shvidkovsky, in his book Russian Architecture and the West, states that "it is like no other Russian building. Nothing similar can be found in the entire millennium of Byzantine tradition from the fifth to the fifteenth century ... a strangeness that astonishes by its unexpectedness, complexity and dazzling interleaving of the manifold details of its design." The cathedral foreshadowed the climax of Russian national architecture in the 17th century.

As part of the program of state atheism, the church was confiscated from the Russian Orthodox community as part of the Soviet Union's antireligious campaigns and has operated as a division of the State Historical Museum since 1928. It was completely secularized in 1929, and remains a federal property of the Russian Federation. The church has been part of the Moscow Kremlin and Red Square UNESCO World Heritage Site since 1990. With the dissolution of the Soviet Union in 1991, weekly Orthodox Christian services with prayer to St. Basil have been restored since 1997.