Castle in Mladá Boleslav, Medieval castle at Staroměstské náměstí, Czech Republic.

Hrad Mladá Boleslav stands on a rocky promontory above the confluence of the Klenice and Jizera rivers at the southern edge of Staroměstské náměstí. Its present form dates from a 1752–1783 conversion into barracks: the palace became four-storeyed with beamed ceilings replacing vaults, the towers received lower hipped roofs, and the north wing was joined to the east wing. The palace wing now houses the State District Archive, while the museum occupies the main building.

A Přemyslid fortified settlement stood here by the turn of the 10th and 11th centuries, and a royal castle was built after the mid-13th century. From 1334 the Michalovice lords held it, then the Krajíř family, who gave it a Gothic-Renaissance form. After 1752 it was rebuilt as barracks, serving the Austrian army and until 1953 the Czechoslovak army.

The castle's name comes from Boleslav, a Přemyslid prince, with "Mladá" (young) added to distinguish it from Stará Boleslav on the Elbe. Since 1972 it has housed the Museum of the Mladá Boleslav Region, and the palace wing holds the State District Archive.

The castle stands at the southern edge of Staroměstské náměstí, above the confluence of the Klenice and Jizera. The museum and the district archive occupy the palace wing; the building has stairs and stone floors, so wear comfortable shoes.

During the Second World War, the castle served as a detention site for Jewish residents from the surrounding region. This difficult chapter remains part of the castle's story today and adds a layer of reflection to any visit.