The Giesen Hills reach their highest point in an unnamed summit, 162.6 metres high.
The wooded northern part of the ridge is crossed by a few footpaths and forest tracks.
Towards the east the land falls away to the Innerste, that flows close by the ridge from south to north.
To the west the hills descend gradually towards the Leine, that runs past them, also in a south to north direction, some 6 kilometres away.
Immediately adjacent to the Giesen Hills to the south is a local military training area, on whose western edge the Osterberg (181 m above NN) rises, but which is not considered part of this landscape unit.