Burg Haag, Medieval castle in Haag in Oberbayern, Germany.

Burg Haag is a medieval fortress in the Bavarian municipality of Haag in Oberbayern, built with a ring wall, tower gate, and outer defensive area. The site sits along Maria-Ward-Straße and includes the remains of a zwinger system that once strengthened the fortification.

Burg Haag was probably built in the 12th century by the noble lords 'de Haga' or 'vom Hage'. Through inheritance or sale it passed to the Gurren von Kirchdorf, then to the Fraunberger family, who ruled until their extinction in 1566. The lordship was raised to an imperial county in 1509 and later granted by Emperor Maximilian II to the Dukes of Bavaria, who reversed the Reformation in the county. Around 1804, during the Napoleonic period, the castle began to be dismantled piece by piece.

The name Haag comes from the noble family 'de Haga' or 'vom Hage', not from the hilltop. From May to October couples can marry in the Schlossturm, and in summer the Schlosshof hosts cultural events. The tower held Haag's local museum from 1981 to 2005.

The tower is closed to visitors except on guided tours, which are held regularly; the tower was shut from 2005 to July 2016 for structural defects. Couples can marry inside the Schlossturm between May and October, and summer cultural events take place in the castle courtyard. The tower is not wheelchair accessible.

The grounds hold both archaeological remains and a preserved zwinger system next to the main tower, showing defensive techniques of the medieval period. This combination of fortification elements allows visitors to see the layers of medieval defensive planning on the spot.