Complex sentence: The Kazan Kremlin (;) is the chief historic citadel of Tatarstan, situated in the city of Kazan, which was built on behest of Ivan the Terrible on the ruins of the former castle of Kazan khans.
Split into simpler sentences: The Kazan Kremlin (;) is the chief historic citadel of Tatarstan, situated in the city of Kazan. It was built on behest of Ivan the Terrible on the ruins of the former castle of Kazan khans.