Schloss Dreiborn, Medieval castle in Schleiden, Germany.

Schloss Dreiborn, also called Burg Dreiborn, is the highest-situated moated castle in the Rhineland, standing in the Dreiborn district of Schleiden. The rectangular complex of rubble stone, partly rendered, was originally two-part and surrounded by a broad moat, entered from the south. Of the late medieval main castle only the free-standing round southwest tower survives, while the three-winged outer bailey keeps its perimeter walls with two round corner towers.

The castle was built from rubble stone, partly plastered, as the highest-situated moated castle in the Rhineland. Philipp Wilhelm Baron von Harff and his wife Anna Catharina von Harff-Dreiborn had the two-storey main house with its lantern-topped corner tower built between 1680 and 1695; their marriage coat of arms survives above the stable portal. The von Harff family held Dreiborn for nearly 400 years, from 1584 until 1982, when it passed by inheritance to the Raitz von Frentz family.

The village of Dreiborn still bears the coat of arms of the Lords of Drimborn: three diagonal roses on the shield, with a helmet topped by a cap bearing another rose, in use since 1325. The castle stayed with the von Harff family for almost 400 years, from 1584 to 1982, before passing by inheritance to the Raitz von Frentz family.

The site lies in Dreiborn, a district of Schleiden in the Euskirchen district, on the Landstraße where a baroque roadside chapel stands. The complex is a moated castle ringed by a broad water ditch, entered from the south; the round southwest tower of the former main castle stands free. The gate leads into the inner courtyard, where the alliance coat of arms of Philipp Wilhelm Baron von Harff and Anna Catharina von Harff-Dreiborn is set above the stable building's portal on the right.

The castle is the highest-situated moated castle in the Rhineland, surrounded by a broad moat. The free-standing round southwest tower is the last remnant of the late-medieval main castle; the three-winged outer bailey still has two round corner towers. The married coat of arms of Philipp Wilhelm Baron von Harff and Anna Catharina von der Horst, from the 1680–1695 rebuilding, survives above the stable portal.