Following Paul's murder, Alexander I assumed power. Mikhail Castle took on several roles, none of which included housing the Tsar. Between Paul's death and 1822, the complex served as barracks for the Imperial Guard, headquarters for the institute for the blind, and the Chancellery of the Ministry of Instruction and Religious Affairs.
In 1822, the Military Engineering School moved into the building, thus the building assumed the name "Engineer's Castle."
Situated immediately outside of the main entrance to the Engineer's Castle sits an equestrian statue of Peter I. The construction of the statue had begun while Peter I was still alive, and his death mask was used as a model. Paul had the statue placed outside of his residence with the inscription "To the great-grandfather, the great-grandson."