Of the highlands on both sides of the river valley, only the Vogelsberg (to its left) and the Gladenbach Uplands (to its right) lie entirely within Middle Hesse.
The western Middle Hesse belongs to the Rhenish Massif and is therefore its oldest part (formed during the Palaeozoic around 300 to 500 million years ago).
Buttes of the Rhenish Massif - like the Sackpfeife (674 m), Angelburg (609 m), Dünsberg (498 m) and Rimberg (498 m); and basalt kuppen, like the Amöneburg, Stoppelberg (402 m) in the north of the Eastern Hintertaunus or the Gleiberg - characterise the landscape.
The most important mountains of the Middle Hesse portion of the Westerwald are the Höllberg (643 m), Auf der Baar (618 m) and Knoten (605 m).
The highest summit in Middle Hesse is the Taufstein in the east of the region in the Vogelsberg mountains, which reaches a height of 773 metres.
The river valleys, especially those of the Lahn and Dill, have incised the landscape deeply in places and represent historically important lines of communication that had a great influence on the developments of towns and the economy.