Ruins of Alte Gleichen Castle

The entire area here had a remarkable skyline in the Middle Ages. The copper engravings by Merian give a rough impression of this. These often offer the only image documentation. Not only were these two castles interesting landmarks, there were several others within sight. A castle complex existed in Reinhausen (at least until 1100 A.D.). In the northeast there was also a considerable castle on the Kronenberg and probably also on the Rohrberg to the south. The Rusteberg also had a large castle complex.

On the twin tops of the same, two towering and widely visible shell limestone mountains between Garte and Wendebachtal, are the remains of two medieval Höhenburegn: the southern castle Altengleichen (426 m above sea level) and the northern castle Neuengleichen (428 m above sea level).
Remains of the former castle complex can still be seen on the grounds of elders. It consisted of a nucleus, which has occupied the inner and highest towering part of the hilltop. Here were the stately residential buildings, of which visible remnants of the walls are present, in addition the towering keep and the castle chapel. Down the hill a foredeck was attached, with residential buildings for the staff, with stables and storage buildings. Through an outer gate and the outer bailey formerly led the only access, as today. The remainder of a ring wall in the shape of a flat ridge wall on the steep slope is preserved around the entire complex.
The edification of the Gleichenburgen by the Counts of Reinhausen falls into the time shortly before 1100. After multiple ownership changes they arrived around 1270 to the Lords of Uslar-Gleichen. Here soon formed the separation of the lines Alten- and Neuengleichen out. Both castles were never conquered by war or siege. Since about the middle of the 16th century, the inhabitants settled in the surrounding farmyards, e.g. in the nearby Appenrode, Bremke and Gelliehausen. Since then, both plants served as quarries.
(Source: Information board at the refuge Neue Gleichen)

It just stands there. And if you want to explore it, you have to conquer the steep castle hill.
A memorial plaque to the fallen from the wars of 1870/71 & 1 & 2 World War was attached to the castle wall