Catherine started a royal art collection which later became the world-famous Hermitage. Several additional buildings (the Minor Hermitage and the Old Hermitage) were commissioned for the growing royal collection of art. The Hermitage Theater was built and the area around the palace was put in order and complemented with the finest houses and palaces. The most prominent embankments on the left bank of the Neva river were upgraded to their present red granite look and the marvelous wrought iron fence of the Summer Gardens was built by Yuri Felten in 1773-86. Under Catherine's patronage science, the arts and trade have flourished.

New buildings for the Russian Academy of Sciences, the Academy of Fine Arts and the first Public Library (now the Russian National Library) were constructed and the large Gostinyi Dvor trading complex was opened on Nevsky Prospect. Many educational institutions were established. In Tsarskoye Selo (now Pushkin) several additions to the royal palace were built. One of these new wings (the Cameron Gallery) served as the living quarters for Catherine the Great herself. The lovely park which surrounds the palaces still bears the mark of Catherine's lively and luxurious court. Among Catherine's many reforms was the reform of St. Petersburg's local administration. In 1766 the position of Mayor "gorodskoi golova" was established.