Burg Mägdeberg, Medieval castle ruins in Mühlhausen-Ehingen, Germany

Burg Mägdeberg is a ruined hilltop castle on the wooded Mägdeberg, a volcanic hill in the Hegau, 1.5 km southwest of Mühlhausen-Ehingen. The ruin stands at about 654 metres above sea level. Its stone-block walls form a closed circuit, divided into an upper castle and a lower bailey; the surviving masonry includes a low arched opening and a massive shell tower flanking the second gate.

Reichenau Abbey had held authority over the Mägdeberg since the 10th century, and Abbot Konrad von Zimmern had the castle built between 1235 and 1240; it was first recorded in 1240 as castrum Megideberc. In 1358 Abbot Eberhard von Brandis sold it to the Habsburg dukes, yet three months later the counts of Württemberg also acquired it and occupied it first. Constance troops destroyed it in 1378, and Eberhard im Bart rebuilt it in 1479.

The name Mägdeberg probably refers to the church on the summit that the Reichenau abbey sought to protect when it built the castle between 1235 and 1240. The site later passed by pledge and lease through the lords of Reischach (1528–1620) and the lords of Rost (1657–1762).

The ruins are freely accessible and reached via Mühlhausen; a hikers' car park lies about 300 metres from the site. The approach runs from the east through the first gate, then up a gently rising ramp supported by a wall to the south, leading to the second gate flanked by a large shell tower.

The castle was destroyed three times before being abandoned around 1700, after which it was quarried for building stone. Its masonry still forms a closed circuit, so the outline of the upper and lower wards survives. The round gun turrets date from the late Middle Ages, added to the high-medieval summit castle.