Schloss Unterbaar, Heritage château in Baar, Germany.

Schloss Unterbaar is a three-story water castle on a small island, with two upper floors above a plain ground floor and four polygonal bay windows rounding the corners. Some first-floor windows retain shell-shaped stucco ornaments. A bridge with a rusted iron railing crosses the remaining moat to the entrance portal, which has a segmental-arched canopy on paired columns and the Himmelsbach coat of arms above.

Michael Riederer (1473–1520) built the castle on a small island; his family sold it in 1563. In 1916 the Himmelsbach timber-merchant family from Freiburg acquired it and remodelled it, facade included, in the 1920s. Gustav Einstein bought it in 1928; after fleeing the Nazis he regained it in 1956 following a long restitution case, and his daughter Else Spirak sold it in 1962 to the Freiherren Groß von Trockau.

The castle's name comes from the Hofmark Unterbaar, the manorial district it headed as a Hofmarkschloss. The Schloßbrauerei Unterbaar, founded in 1608, is run by the Freiherren Groß von Trockau, who bought the estate in 1962 and leave the castle itself empty. The brewery describes itself as one of Germany's oldest documented private breweries.

The castle is empty and not open to visitors; it stands in dense overgrowth behind a bridge with a rusted iron railing, and the moat survives only here. View it from the public path in Unterbaar and do not enter the grounds.

The castle grounds contain one of Germany's oldest privately owned breweries, founded in 1608 and still operational today. This represents a rare example of continuous brewing tradition preserved in one location.