The Peter and Paul Fortress (Petropavlovskaya Krepost) is the original citadel of St. Petersburg, Russia, founded by Peter the Great in 1703 and built to Domenico Trezzini's designs from 1706-1740. In the early 20th century, it was still used as a prison by the tsarist government.
Today it has been adapted as the central and most important part of the State Museum of Saint Petersburg History. The museum has gradually become virtually the sole owner of the fortress building, except the structure occupied by the Saint Petersburg Mint.