Château de Morimont, Medieval castle ruins in Oberlarg, France

Château de Morimont is a ruined castle on a rocky crest at 522 m in Oberlarg, Haut-Rhin, Alsace, built of Jurassic limestone with lime mortar. Its oldest part is a 13th–14th-century U-shaped keep; the north hall of 1552 measures 51 by 7.5 m and retains a barrel-vaulted cellar and two spiral staircases. The southwest Schlossturm and parts of the west and south curtain walls date from the 15th century.

First documented in 1271, when the Count of Ferrette made an oblation of it to the Bishop of Basel. Destroyed by the Basel earthquake of 1356, it was rebuilt by the Morimont family, vassals of the Ferrettes, and passed with them to the Habsburgs. Pierre de Morimont turned it into a fortress adapted to firearms. After the Thirty Years' War it was given by Louis XIV to the Vignacourt family in 1641.

The fortress shows how military design and local building methods came together in a single structure, visible in the stone walls and towers. Visitors can observe how the architecture reflects its position guarding a regional border.

The site is connected to hiking paths that run through the surrounding landscape and offer good opportunities for exploration. Sturdy footwear is recommended since the ground is uneven and the paths climb toward the hilltop.

The southern tower contains underground vaults designed for a specific type of cannon placement and fire control. This construction reveals how builders of that era worked out their defense strategies in stone.