The Cathedral of the Protection of Most Holy Theotokos on the Moat (Russian: Собор Покрова пресвятой Богородицы, что на Рву) or Pokrovsky Cathedral (Russian: Покровский собор) are official names for a Russian Orthodox church in Red Square in Moscow. The church is also called the Cathedral of St. Vasily the Blessed (Russian: Собор Василия Блаженного), 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.
The original building, known as "Trinity Church" and later "Trinity Cathedral", contained eight side churches arranged around the ninth, central church of Intercession; the tenth church was erected in 1588 over the grave of venerated local saint Vasily (Basil). In the 16th and 17th centuries the church, perceived as the earthly symbol of the Heavenly City, as happens to all churches in Byzantine Christianity, 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.
Moscow (/ˈmɒskaʊ/ or /ˈmɒskoʊ/; Russian: Москва, tr.Moskva; IPA: [mɐˈskva] ( listen)) is the capital city and the most populous federal subject of Russia. The city is a major political, economic, cultural and scientific center in Russia and in Europe. According to Forbes 2012, Moscow has the second largest community of billionaires in the world. Moscow is the northernmost megacity on Earth, the most populous city in Europe, and the 6th largest city proper in the world. It is the largest city in Russia with a population, according to the 2010 Census, of 11,503,501. By its territorial expansion on July 1, 2012 southwest into the Moscow Oblast, the capital increased its area 2.5 times; from about 1,000 square kilometers (390 sq mi) up to 2,511 square kilometers (970 sq mi), and gained additional population of 233,000 people.