The impressive 60 metre high tower was built between 1505 and 1508. The adjoining belfry was built 15 years later and contains some 20 bells. The biggest bell (the world's largest no less) however was too big to remain in its place and sits to the rear of the tower with a huge crack in it. In recent years the belfry has become home to a new high-tech exhibition which illustrates the history of the Kremlin's changing architectural styles. It is also now possible to climb up the tower (that's 137 steps to be exact) to admire the view over central Moscow and get a close up look at the bells.
You must buy a separate ticket for the Ivan's Bell Tower excursion at the excursion office before you enter the Kremlin and you can only go up the tower at the time indicated on your ticket.