Mozhaysk Kremlin, Medieval fortress in Mozhaysk, Russia

Mozhaysk Kremlin is a former white-stone fortress on Cathedral Hill above the Mozhayka River; almost nothing of it stands today. What remains are earthen ramparts holding fragments of white-stone towers and walls, plus the intact gate with 11 metres of wall built into the New St Nicholas Cathedral, whose red brick bell tower rises above the grassy slope.

A wooden citadel stood here from the 12th century; it was burned by the Mongols in 1293 and destroyed by Tokhtamysh in 1382, after which the gate tower was rebuilt in stone. In 1618 the walls withstood a joint siege by Prince Władysław of Poland and Hetman Żółkiewski, the last siege of the wooden fortress. The stone kremlin was built in 1624–1626 on the same irregular pentagon plan, with walls resting on six towers and the Mozhayka River.

The New St Nicholas Cathedral, built in 1812, stands on the site of the Kremlin's St Nicholas Gate. After World War II it housed a knitting factory, and since 1994 services have resumed there. The adjacent Peter and Paul Church, built in 1849–1852 on the site of the demolished Old St Nicholas Cathedral, has been a town museum since the 1960s and is not used as a church.

The fortress sits about two hours by train from Moscow, with the main station providing the primary arrival point. Once there, wear sturdy shoes as the ground is uneven and the site sits on sloping terrain.

The 2006 excavation inside the New St Nicholas Cathedral uncovered a fragment of the 11th–12th-century rampart: horizontally laid logs held by hooked beams set into the earth. A matching construction was found in the Moscow Kremlin in 1959, supporting the idea that Moscow and Mozhaysk were fortified under one building programme along the route through the Vyatichi lands.