Castle Nižbor, Medieval castle in Nižbor, Czech Republic.

Nižbor is a castle in Nižbor, Central Bohemia, built on a sloping promontory above the confluence of the Berounka and Habrový potok. It began as a two-part Gothic castle with two palaces and a polygonal chapel, later rebuilt in Renaissance and Baroque styles. The south palace collapsed in the 14th century, and its outer wall was reused as a rampart.

Nižbor was founded in the 13th century by King Přemysl Otakar II, though older literature names Václav I as possible founder. In 1425 a Hussite detachment of 120 men took the neglected castle, but was soon defeated by Aleš of Šternberk and Hanuš of Kolovrat. From 1601 Konrád Šanovec ze Šanova began Renaissance alterations; under Jan Josef of Valdštejn it became a Baroque château.

The castle's name derives from Miesenburg, after the river Mže, the old name of the Berounka. Since 2004 the building houses a multimedia exhibition and information centre on Celtic culture, covering the Celts' crafts, gods and wars.

The castle stands on a sloping spur above the confluence of the Berounka and Habrový potok. In the courtyard look for two sundials: the left one shows true local time, the right one Old Bohemian time counted from the previous sunset. The grounds were bought by the village in 1997 and the roof was fully repaired in 1971.

The courtyard holds two sundials: the left one shows true local time and bears the Latin motto "Sine sole nequid sum" (Without the sun I am nothing), while the right one shows Old Czech time, counting hours elapsed since the previous sunset.