One of the most symbolic constructions in Russia's history, the Moscow Kremlin Wall can be traced back to the 12th century when Moscow was founded in 1147. The original outpost was surrounded by the first walls in 1156, built by Yuri Dolgoruki, prince of Suzdal, which were most likely a simple wooden fence with guard towers. Destroyed in 1238 by the Mongol-Tartar invasion, the Moscow Kremlin was rebuilt by the Russian Knyaz Ivan Kalita. In 1339-1340 he erected a bigger fortress on the site of the original outpost which was defended by massive oak walls. Thought to be an impenetrable defence from raids, it was proven to be useless against raids which burned Moscow in 1365.