Grenzau Castle

Höhr-Grenzhausen, Germany, Germany

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Grenzau Castle near Höhr-Grenzhausen in Rhineland-Palatinate, Germany, is a medieval spur castle ruin built around 1210 by Heinrich I von Isenburg as Burg Gransioie—meaning "great joy" in Old French—at 250 meters elevation with two baileys, an inner ward, and an outer ward to the west.

Captured by Trier's Archbishop Baldwin in 1346 during the Grenzau Feud, it later housed Isenburg lines, gained artillery bastions and a roundel in 1557, and was torched by French troops in 1635 during the Thirty Years' War before falling into decay under Trier ownership.

Its standout feature is Germany's only triangular 32-meter-high bergfried from the mid-13th century, plus a 14th-century gatehouse with round tower; privately owned since 1925 and preserved by a family society after 1953, it opens summers for visitors to explore its defensive architecture.