When you are standing in the area where the Congregational Mosque was once built every building could be seen from this platform, the East Mausoleum being one of them.
This mausoleum contains a tomb of Bolgar nobility, crowned by a traditional Eastern tent style roof. Inside the 700 year old building is an exhibit displaying the stages of the life settlement as an example of the archaeological excavation of the 11th century. B.C.E.
The Eastern Mausoleum (St. Nicholas Church) is another example of Muslim architecture of the 14th century. The small holes in the dome, which are not functional, are very interesting. Some experts suggest that they are a special tradition of Bulgar architecture; others believe that they are associated with the appearance of yurts.At the beginning of the 18th century, after the foundation of the monastery, the mausoleum was turned into an Orthodox church and consecrated in the name of Nicholas the Wonderer. In 1994, an Islamic crescent was again installed on its top.