Burg Balduinseck, Medieval castle ruins in Buch, Germany.

Burg Balduinseck is a ruined hilltop castle on a narrow rocky spur about 20 meters high at the confluence of the Wohnrother Bach and Schumbach streams. Its four-story residential tower, 22.7 by 14.4 meters with walls up to 2.5 meters thick, still stands 18 meters tall. The ruin extends about 55 meters east-west and up to 20 meters wide, with remains of a round tower and ring wall to the west.

Archbishop Baldwin of Trier commissioned the castle in 1325 as a defensive fortification against the County of Sponheim. Over centuries it gradually deteriorated through natural weathering rather than military conflict.

The structure displays French architectural influences and reveals medieval construction methods through its preserved stonework and remaining staircase fragments. The design shows the craftsmanship and building standards of that era.

The castle sits along the L203 road between Buch and Mastershausen with free entry and on-site parking available. Information panels on location help explain the site's features and guide your visit.

The residential tower was built first and stands directly behind the neck ditch on the attack side, the opposite of the usual castle layout; the same arrangement appears at Balduin von Luxemburg's Baldenau. A round tower and ring wall were added later to the west.