Central fortress in medieval Russian cities, usually located at a strategic point along a river and separated from the surrounding parts of the city by a wall with ramparts, moat, towers, and battlements. Several capitals of principalities were built around old kremlins, which generally contained cathedrals, palaces, governmental offices, and munitions stores. The Moscow Kremlin (established 1156) served as the centre of Russian government until 1712 and again after 1918. Its crenellated brick walls and 20 towers were built in the 15th century by Italian architects. The palaces, cathedrals, and government buildings within the walls encompass a variety of styles, including Byzantine, Russian Baroque, and Classical.