The Church of St. Casimir was built by the Jesuits in 1604-1635 but was destroyed by fire three times, which was cause for major reconstruction in 1750. Much of it was destroyed in 1812, when Napoleon's army used it as a granary. It became a Russian Orthodox church in the 19th century, when onion domes were added. It was used by the German army as a Lutheran church during World War I and then returned to the Jesuits. The Soviets used the church as a museum of atheism starting in 1963. It was reconsecrated in 1991.