Burg Sulzburg, Medieval castle ruins in Unterlenningen, Germany

Burg Sulzburg is a late medieval spur castle ruin at 492 m above sea level overlooking the Lauter valley near Unterlenningen. Its rectangular layout comprises a Vorburg and a Kernburg enclosed by an outer Zwinger. The shield wall linking the two parts is 24 m long, 1.9 m thick and 7.5 m high, built of rubble stone with dark corner quoins. Behind it stand a large economic building with barn, stables and vaulted cellar, and a band and wagon house.

The Sulzburg was first recorded in 1335 as "Festi Sulzpurch", when the Lords of Neidlingen pledged not to use it against Württemberg. In 1341 an inheritance dispute divided it between two Neidlingen brothers. Imperial troops occupied and destroyed it in 1634 during the Thirty Years' War, but it was rebuilt. Around 1700 it became uninhabitable, and demolition began in 1751 before being halted; the ruin was secured and partly rebuilt in 1966/67.

The name Sulzburg is first recorded in 1335 as "Festi Sulzpurch". The castle was a Württemberg fief held by the Speth family from about 1395, and a castle bailiff still lived in the new palace around 1700. A 1712 description lists the new palace's six larger rooms, nine chambers, two kitchens, four stables and two cellars.

The ruins are reachable on foot in about 15 minutes from Unterlenningen's town center and remain accessible year-round. The path is easy to find and no special equipment is needed to explore the site.

The two palaces differ sharply in size: the old one measures 13.6 by 4.2 metres, the new one 17.2 by 9.8 metres. A 1712 description lists the new palace's rooms, including six larger chambers, nine small rooms, two kitchens, four stables and two cellars. A pointed barrel vault of its cellar survives by the gatehouse, where a viewing terrace was built on the old foundations in 1966/67.