Mir Castle was raised as a fortress and then, within a single lifetime, remodelled into a palace — and both jobs are still legible on the same walls. Duke Yuri Ilinich put up the five brick towers between roughly 1522 and 1526: walls three metres thick and about thirteen metres high, wrapped around a courtyard some 75 metres to a side, each tower slotted with firing loops and finished in Gothic battlements. When his line died out in 1568 the castle passed to Mikołaj Krzysztof Radziwiłł, one of the great magnates of the Grand Duchy of Lithuania, who pushed a three-storey residence against the eastern and northern walls and dressed the whole thing in the Renaissance — limestone portals, balconies, and pale plaster niches set into raw red brick. That collision of defence and display, carried by one building, is what earned the complex UNESCO World Heritage status in 2000.
What came after was rougher. The Battle of Mir in 1812 left the castle burnt out; in May 1942 the Germans drove the town's surviving Jews inside these walls, and after a warning reached the ghetto some 200 people slipped away on the night of 10 August, three days before the rest were shot. Soviet families then lived in flats inside the shell until 1956. Restoration began in 1983 and only finished on 16 December 2010, when the castle opened as a museum of 42 halls — the Portrait Hall reset to the 1740s, Prince Michał's library left as it stood in 1930. You climb worn spiral stairs into the west tower and come out on the wall walk above the red tiled roofs. Outside, the earth ramparts are 17th-century, while the broad pond below them was dug only in the 1890s, after a bastion was levelled to make room for it.