Burg Neuenburg, Medieval castle ruins in Durach, Germany.

Burg Neuenburg is a ruined hilltop castle on a forested spur southeast of Durach, built after 1300 for a branch of the Lords of Sulzberg. The Durach river loops around three sides, and two neck ditches with an intermediate wall cut the site off from the ridge to the north. In the northeast corner stands the stump of the bergfried, up to six metres high and about 9.8 by 9.4 metres in plan, with its original high entrance walled up in the west wall; the north and east walls were destroyed by blasting around 1893. A long wall up to three metres high runs west from the tower, and foundations of a semicircular shell tower remain in the southwest corner.

Built after 1300 by a branch of the Lords of Sulzberg, the hilltop castle replaced an older service castle of the Kempten abbey and was called "Neusulzberg". In 1380 it passed to the Schellenberg family, and in 1421 they sold the fief to the Kempten abbey, confirmed by Emperor Sigismund in 1436. From 1455 it housed a penal institution; the last bailiff left in 1642 and the castle was abandoned and quarried.

The name Neuenburg, or "Neusulzberg", marks it as the "new castle" of the Sulzberg line, replacing an older Kempten ministerialis stronghold on the spur. A stone memorial tablet set into the west wall of the tower stump was installed in 1926 on the initiative of Otto Merkt, Kempten's mayor and a castle researcher. In the valley below, the marked "Wasserweg" trail through the Durach loop carries information boards on the site.

The ruins sit on a forested hill and are reachable on foot, with sturdy shoes recommended due to uneven terrain. The site is best visited during dry weather, as the climb can become slippery.

Archaeological excavations in 1992 uncovered traces of a blast shaft, showing that parts of the structure were deliberately demolished. This destruction detail reveals the violent end of the castle rather than simple decay over time.