Only accessible to clergymen and altar servers, the altar is the holiest place in any church. The roof of the altar has a starry sky painted with Holy Ghost depicted as a dove in the middle of it and in the center of the altar is the altar table. The one in Uspenski is originally from the Valamo Monastery, which was ceded to Soviet Union during the 2nd world war. There are also multiple icons in the altar, the most impressive of which, Jesus Christ sitting on the throne. The altar table is where the holiest ceremonies, such as Eucharist, are conducted and only clergymen are allowed to touch it or the items that rest on top of it.  

You can see inside the altar during divine services, during which the royal doors are opened. Only the clergymen can walk through the doors and other altar servers have to use the side doors which depict angels Michael and Gabriel on them.