Burgruine Hardeck, Castle ruin in Lorbach, Germany.

Burgruine Hardeck is a ruined hilltop castle on a 296-metre basalt cone in the Lorbach district southwest of Büdingen. Its oval rampart encloses 8,660 square metres, with an outer wall about 340 metres around and a ditch up to nine metres deep on the north side. Inside, low wall stumps, a round tower foundation in the south and a raised platform mark the former buildings and hall.

The castle was probably built in the 10th or 11th century by unknown builders. It was first mentioned in writing in 1289 as "... tria in campo versus Hardeckin". In 1405 it was still the seat of an administrator, but when the last one, Eckart Riedesel, moved to Büdingen in 1464, the castle was abandoned as an official residence. It was uninhabited from 1471 and was demolished by Austrian troops in 1794 or 1796, with the material used for road building.

The name Hardeck likely comes from the hard basalt rock of the hill. The castle had sightlines to Ronneburg, Glauburg and later Büdingen, guarding roads from the Main plain to the Vogelsberg. The medieval Antsanvia road, called Reffenstraße here, ran within sight.

The site is located on a hilltop and offers good views of the surrounding area from above. The northern section shows a deeper ditch with visible stone wall remnants that visitors should watch for when exploring.

Water was a major challenge for those living here, as the nearest spring lay about two kilometers away. Supplying the settlement with fresh water required difficult transport over long distances, making daily life on the hilltop demanding.