The Kazan Kremlin includes many old buildings, the oldest of which is the Annunciation Cathedral (1554–1562), the only 16th-century Russian church to have six piers and five apses.

The renowned Pskov architects Postnik Yakovlev and Ivan Shirjay (called Barma) were invited by the Tzar to rebuild the Kazan Kremlin in stone.

The most conspicuous landmark of the Kazan Kremlin is the leaning Söyembikä Tower, which probably goes back to the reign of Peter the Great.

Also of interest are snow-white towers and walls, erected in the 16th and 17th centuries but later renovated; the Kul Sharif Mosque, recently rebuilt inside the citadel; and the Governor's House (1843–1853), designed by Konstantin Thon, now the Palace of the President of the Republic of Tatarstan.

On July 21, 2005, the feast day of the holy icon "Theotokos of Kazan", in the presence of the crowd of 10,000 pilgrims, Patriarch Alexius II and Mintimer Shaeymiev placed at the newly restored Annunciation Cathedral the holiest copy of the long-lost icon, which had been returned to Russia in 2004 by Pope John Paul II shortly before his death.