the Big House) is an office building located at 4 Liteyny Avenue in Saint Petersburg, Russia.

It is the headquarters of the local Saint Petersburg and Leningrad Oblast branches of the Federal Security Service of Russia (FSB) and Main Department of the Ministry of Internal Affairs.

It was originally constructed in 1931–32 for the Joint State Political Directorate (OGPU), the secret police of the Soviet Union at the time.

[1] The building was designed by Soviet architects Noi Trotsky, Alexander Gegello and Andrey Ol in the late Constructivist style.

The Bolshoy Dom building is part of a larger complex which includes the detention facility on Shpalernaya Street, with both gaining notoriety as a prison during the Great Purge under Joseph Stalin.