Burg Ardeck, Medieval castle ruins in Holzheim, Germany

Burg Ardeck is a castle ruin located on a hillside overlooking the Aar River valley near Holzheim. It displays preserved wall sections and a tower approximately 21 meters tall.

Burg Ardeck was first mentioned in 1395 in Tilemann Elhen von Wolfhagen's Limburg Chronicle, which also notes remains of an earlier structure. It served the County of Diez as a border fortification against Katzenelnbogen and to watch the route from the Aartal via Holzheim to Limburg. From 1467 it was the seat of the von Dietrich von Diez family as a fief; after the family died out in 1727 it was abandoned and by 1740 was described as completely ruined.

The name "Prinz von Ardeck" was granted in 1876 by Prussian King Wilhelm I to Marie von Hanau, divorced wife of Landgrave Wilhelm of Hessen-Philippsthal-Barchfeld, and to her descendants, with the style of Serene Highness. The title passed to her children from that marriage; the line ended with Luise, Princess zur Lippe, born Princess von Ardeck (1868–1959).

Entry to the ruins is free and available around the clock, with parking accessible via Schone Aussicht road near Holzheim. Sturdy footwear is helpful since the path to the site climbs steeply.

The fortress displays an unusual construction technique where the tower and curtain wall were built separately without interlocking masonry bonds. This suggests that fortification components were added to the site at different periods.