The Menshikov Palace on the Universitetskaya Embankment of Vasilievsky Island was the grandest house in early St Petersburg — built in 1710 for Peter the Great's right-hand man, and finished a decade before the Winter Palace existed in its present form. It is now a branch of the Hermitage covering early 18th-century Russian culture, with restored interiors hung with portraits, Dutch tile rooms, period furniture, and Menshikov's own collection of curiosities.
It is rarely crowded — most Hermitage visitors never make it across the river — and well worth the short walk from the main museum. The tour gives a useful sense of how Petrine-era court life worked: the imported European craftsmen, the absurd levels of ceremony, and the precarious power-juggling that defined Peter's early reign. The same Hermitage ticket gets you in.