Ostrovsky Square, Heritage site in Tsentralny District, Saint Petersburg, Russia

Ostrovsky Square is an ensemble laid out by architects K. I. Rossi and A. A. Modyui in the 19th century, where Nevsky Prospekt, Zodchego Rossi Street, Malaya Sadovaya Street and Krylova Lane meet. The Alexandrinsky Theater faces the garden holding the bronze monument to Catherine II, a crowned figure with scepter above seated and standing companions on a tall pedestal. The National Library of Russia closes the western end.

The creation of the site followed the construction of the theater, opening part of the palace gardens to the public. The monument was added later, and the library on the western side completed the spatial ensemble.

Locals often call the theater the Alexandrinka, showing how closely the city's life is tied to the building. The garden serves as a meeting point for walks and conversation, while the library continues its role as a reading center.

The square lies where Nevsky Prospekt meets Zodchego Rossi Street, Malaya Sadovaya Street and Krylova Lane, so it can be reached on foot from several directions. The Catherine II monument stands on a raised platform of shallow curved steps ringed by posts and a hanging chain, with the garden behind it. The Alexandrinsky Theater faces the garden from the east and the National Library closes the west end.

The architect planned the surrounding streets with exact proportions between building heights and street widths. This mathematical harmony can still be felt when walking through the area today.