Castle Kastellaun, Medieval castle ruins in Kastellaun, Germany

Castle Kastellaun is a hilltop ruin in the Rhein-Hunsrück region with surviving wall sections, a tower, and distinct areas that reveal its original layout. The site also includes a documentation center that records the structure's architectural development across centuries.

Kastellaun Castle was built in the 13th century and is first documented in 1248 as a possession of the Counts of Sponheim; in 1301 it became the residence of Count Simon II of Sponheim. Archbishop Baldwin of Trier besieged it in 1321, and after 1340 it was run by bailiffs. In 1689 French troops blew it up in the War of the Palatine Succession, and it was never rebuilt.

The castle's name appears as Kestilun in a 1226 document, though it is unclear whether the named men Hilger and Gerhard von Kestellin took their name from the castle or the town. The former palas now serves as an open-air stage for theatre, and on summer Sundays the town runs a children's programme on the site. In the lower bailey, a documentation centre dedicated on 9 September 2007 displays a reconstruction of the Bell wagon burial found in 1938, Celtic pottery and fibulae.

The site is easy to explore on foot and offers good viewpoints across the surrounding landscape, though some areas are uneven due to the ruined state. Wear sturdy shoes as the paths are not level everywhere.

The powder tower survives on one side only: when French troops blew up the castle in 1689, part of the explosive charge failed to detonate. The tower's remaining half still stands in the western ruin of the palas, which is visible from far off.