Apanaev mosque (other names - the Second Cathedral, Bai, Cave) is located in the Old Tatar Sloboda. The mosque was built in 1768-1771, money Tatar Yakub merchant Sultangaleeva. The leaders of the Muslim community of Kazan received the permission of Catherine II for the construction of two mosques of stone. Second built mosque was the mosque of al-Marjani.

The new mosque was named Apanaev in honor of merchants Apanaevs containing a mosque at his own expense. The name "Cave" stuck in the mosque in connection with the hilly terrain of the surrounding countryside and the nearby steep banks.

In the architectural style of the mosque there are elements of Russian (Moscow) and Baroque elements, made in the Tatar traditions of decorative art.The first mosque was one room, but later on the project P. I. Romanova, the mosque was built on two floors. In style it consistent with the original architectural design. The mosque became a two-story, two-hall, minaret, located on the roof of the building.In 1882, around the mosque erected a fence of brick with single storey shop. In 1887 at the shop had a second floor.

In 1930, the mosque was closed. During the Soviet period in the history of the mosque collapsed arches halls and minaret. Decorative elements of the interior were cut off, the internal volume is divided into three floors. In the building of the kindergarten has been opened.

In 1995 the building was given to the madrasah. In 2007-2011 the mosque building was comprehensively renovated. By the beginning of the restoration of the initial form of building of the mosque is almost nothing left. The restoration restored the ruined minaret, restored internal division into two floors. Old interior, unfortunately, was completely lost.

Nowadays Apanaev mosque – acting. It is a monument of religious architecture of the 18th century.