Short answers, pulled from the story.
The Kazan Kremlin was declared a World Heritage Site in 2000. It is the chief historic citadel of Kazan, Russia, and was originally built at the order of Ivan the Terrible on the ruins of the castle of Kazan khans.
The Pskov architects Postnik Yakovlev and Ivan Shirjay, also known as Barma, were invited by Ivan the Terrible to rebuild the Kazan Kremlin in stone. They were renowned builders of their time.
The Annunciation Cathedral, built between 1554 and 1562, is the only sixteenth-century Russian church with six piers and five apses. It is also constructed of local pale sandstone rather than brick, setting it apart from other Russian churches of the era.
The Kul Sharif Mosque was rebuilt inside the Kremlin on the site where the Khanate of Kazan's principal mosque had presumably stood before 1552. Its opening on the 24th of June 2005 drew roughly seventeen thousand people and delegations from forty countries.
The Söyembikä Tower is the Kremlin's most conspicuous landmark, known for its visible lean. It probably dates to the reign of Peter the Great, and a well-known legend connects it to the last queen of the Khanate of Kazan.
The Annunciation Cathedral's bell tower, built in five tiers at Ivan the Terrible's urging, was pulled down by Soviet authorities in 1930. The Church of St. Nicholas and the Cathedral of the Saviour's Transfiguration, which belonged to the nearby Spassky Monastery, were destroyed during Joseph Stalin's rule.