The date of construction of Söyembikä Tower is uncertain. Some scholars date it to before the conquest of Kazan by Ivan the Terrible in 1552. Others put the date later; in the 17th or 18th centuries. (Source: Wikipedia)
The Annunciation Cathedral dates from 1561 to 1562. It has been reconstructed several times.
The Spassky tower was first built in 1556-1562. It has been developed and re-built several times over the years.
Qol Sharif Mosque is a new addition to the Kazan Kremlin. It was opened in 2005. It is the largest mosque in Europe. (Source: Wikipedia)