Passage: Zubtsov was first mentioned in a chronicle in 1216. Due to its location on the Volga, it controlled one of the versions of the Trade route from the Varangians to the Greeks. In the Middle Ages, it was a border fortress of Principality of Tver. Between 1318 and 1460, separate Zubtsov Principality existed with the seat in Zubtsov. It was subordinate to the Tver principality. In 1460, it was abolished and merged back to Principality of Tver. The Grand Duchy of Moscow annexed it with the rest of Principality of Tver in 1485. Subsequently, the town was important chiefly as a flax trade market. Its Neoclassical cathedral was constructed in 1801.

Question: Which year was it annexed
1485