Burg Montfort, Medieval castle ruins in Hallgarten, Germany.

Burg Montfort is a medieval castle ruin in Hallgarten with remains of several structures including a gate house, foundations of the main tower, and two residential towers that reach three stories high. The site is enclosed by outer walls of the former outer bailey that define the layout.

The Counts of Veldenz built the castle around 1240 to control a nearby military road, installing Eberhard von Lautern as their vassal. His family, known as von Montfort from 1247, held it until 1432. In the 15th century the co-owners turned to highway robbery; in 1456 troops of the Archbishop of Mainz and the Elector Palatine captured and destroyed the castle. In 1480 Simon Boos von Waldeck received it as a hereditary fief with permission to rebuild, but it remained a ruin.

The castle's name comes from the von Lautern family, who were enfeoffed with the site and from 1247 called themselves "von Montfort". In the 15th century, the castle's co-owners turned to highway robbery, prompting its destruction in 1456 by troops of the Archbishop of Mainz and the Elector Palatine. The ruin later passed to Simon Boos von Waldeck in 1480, whose family had been co-owners since the late 14th century.

The 9 m high keep is reached from inside the residential tower via a 34-step metal spiral staircase and then along the outer wall of the inner bailey; a metal railing secures the top. The ruin stands on a wooded 280 m hill between Hallgarten and Duchroth, so paths are unpaved and sturdy footwear helps.

The ruin was long split among four private forest owners and neighbours; only in 1969 did the Bad Kreuznach district take it over, secure it and renovate it after safety requirements from the supervisory authority. The 9 m stump of the bergfried is walkable and serves as a viewpoint.