What was the greatest accomplishment of Ivan 3?

Ivan III, also known as Ivan the Great, is best known for unifying the Russian principalities and laying the foundation for the centralized Russian state. His most significant accomplishment was the successful overthrow of Mongol rule, which had dominated Russia for over two centuries, culminating in the decisive victory at the Great Stand on the Ugra River in 1480. This achievement not only asserted Russian independence but also established Ivan III as a powerful ruler, enhancing the influence and territory of the Grand Duchy of Moscow. His reign marked the beginning of a new era in Russian history, leading to the eventual emergence of the Tsardom of Russia.