Erichsburg, Medieval castle in Dassel, Germany.

Erichsburg is a medieval castle in Dassel featuring thick stone walls, defensive towers, and fortified structures. The layout shows typical castle design with reinforced ramparts and buildings arranged around a central courtyard.

Duke Eric I of Brunswick-Lüneburg built Erichsburg between 1527 and 1530, naming it after his son and heir, the future Duke Eric II, born in 1528. It replaced Hunnesrück Castle, which the counts of Dassel had founded in the 13th century and which was shelled from the Hatop heights and taken in 1521 during the Hildesheim Diocesan Feud. Duke Julius of Wolfenbüttel had it extended between 1604 and 1612 under master builder Paul Francke; by 1688 parts of the first building phase were demolished as dilapidated.

The castle takes its name from Duke Eric II, born in 1528, for whom his father Eric I had it built between 1527 and 1530. From 1891 to 1980 the Hanoverian State Church leased the complex, running a preachers' seminary there and, from 1971, a holiday home. The chapel and a sample room have been restored in recent years.

The castle is privately owned since 2019 and not open to visitors; the grounds with lawns, paths, old trees, moats, ponds and ramparts were described as well kept in 2012. It stands on the eastern edge of the Erichsburg settlement, a part of Dassel's Hunnesrück district, surrounded by the Försterteich, Langerteich, Eckteich and Schulteich ponds, with the Bremke stream passing to the south.

The castle still preserves sections of an old moat system that once held water and reinforced the defensive line. This system remains partially visible today and shows how carefully the fortifications were planned.