The Peter and Paul Cathedral (Russian: Петропавловский собор) is a Russian Orthodox cathedral located inside the Peter and Paul Fortress in St. Petersburg, Russia. It is the first and oldest landmark in St. Petersburg, built between 1712 and 1733 on Hare Island along the Neva River. Both the cathedral and the fortress were originally built under Peter the Great.

Work began on the first, wooden church to be erected on the site just one month after St. Petersburg was officially founded, and the church was consecrated on April 1, 1704. In 1712, the current, stone Peter and Paul Cathedral started to be built, to a design by Domenico Trezzini. This one took slightly longer to build - 20 years, in fact - and was consecrated on June 29, 1733.

The Peter and Paul Cathedral marked a radical departure from traditional Orthodox churches, being built in early Baroque style. Its rectangular shape, bell-tower, and landmark needle are all features borrowed from the protestant churches of Western Europe - the influence of Dutch architecture is particularly visible - all of which was in accordance with Peter's wishes.

The inside of the cathedral holds a fantastic iconostasis, completed by a group of more than forty Moscow architects under Ivan Zarudny from 1722-1727. Whereas the architectural style of the cathedral is similar in style to the Lutheran church, the painting of the iconostasis is more in the spirit of Catholic Church icons. The walls of the cathedral are also embellished with paintings of various bible themes, including many paintings of gospel stories by artists of the early and mid 18th century.