One of the oldest architectural monuments in Omsk is the building of the former fortress guardhouse, constructed between 1781 and 1785. It was built in the popular style of Elizabethan Baroque of that time. The building is made of brick, which was later covered with lime plaster. The name of the project author remains unknown, however, despite its original purpose, the structure has become one of the most original and memorable in Omsk.

Throughout its history, the Omsk guardhouse has been mentioned in the memoirs of many famous travelers. Architect Kryachkov cited this building as a vivid example of the architectural splendor of the city in his descriptions of Siberian beauty. While many examples of Elizabethan Baroque have survived in Moscow and St. Petersburg, this style is quite rare for Siberia.

Initially, the building served as a place for the commandant's office, fortress guard, and for soldiers who misbehaved. In the 19th century, political prisoners were held on the first floor. The most interesting period in the history of the guardhouse is associated with the stay of the 'oblastniki', including the scholar Grigory Potanin, who were sentenced in 1865 for promoting separatism. The great Russian writer Fyodor Mikhailovich Dostoevsky also spent some time here.

It is noteworthy that the cells for political prisoners were locked only at night, and during the day, the detainees could freely go outside and receive guests. The second floor was immediately occupied by the garrison school, which became the first educational institution in Omsk. Later, it was transformed into the Military Orphanage and the School of Asian Languages.

In the second half of the 19th century, the guardhouse building received a gentler roof, and during the Soviet era, the tower with the year of construction was demolished (the tower has now been restored). In the 1960s, various utility extensions appeared here, and only in the 1980s did the building receive protected status. It now belongs to the fortress museum.