Mariinsky Palace is a 19th-century neoclassical palace on St Isaac's Square, built in 1839-44 for Grand Duchess Maria Nikolaevna. Its position near St Isaac's Cathedral and the Blue Bridge makes it part of one of central St Petersburg's strongest architectural walks.
The palace now serves a government role, so most visitors come for the exterior rather than an interior tour. It is still worth noting for its scale, symmetry, and place in the imperial city plan around the square.