1. Priory Palace MuseumGatchina Priory Palace is an original palace in Gatchina , Russia. It was built in 1799 by the architect N. A. Lvov on the shore of the Black Lake . Constructed for the Russian Grand Priory of the Order of St John, it was presented to the Order by a decree of Paul I of Russia dated August 23, 1799. From Wikipedia, the free encyclopedia.