On 8 February 1819, the decree of Emperor Alexander I reorganized the Main Pedagogical Institute into St Petersburg University which was actually a renaming — the University regained its historical name. This was the end of the initial period of organization and development of the University in St Petersburg.
In 1821 the University was renamed St Petersburg Imperial University.
Initially, there were 3 faculties: History and Philology, Law and Philosophy, Physics and Mathematics. The system of faculties was borrowed from German universities. In 1855, the Faculty of Oriental Languages was added to them. Such a structure of the University existed until 1918.
In 1830, the Twelve Colleges building designed by the architect Domenico Trezzini was given to the University.