In the Middle Ages, the imposing Pferdebergwarte towered on the highest peak of the Pferdeberg, an important part of the Duderstadt Landwehr and an integral part of the city's defense system. The first written mention of this defense system can be found in the city's accounting book (Annale) from 1445, where it is referred to as the "Horse Guard". It is believed to have been built towards the end of the 14th century, while Duderstadt was embroiled in a feud with Hans von Osterode.
In times of danger, the Horse Mountain Observatory played a crucial role in warning the city. By using fire signals, the tower keeper of St. Cyriacus Church could be alerted, giving the city enough lead time to take appropriate defensive measures. This high-altitude position allowed for effective surveillance of the surrounding area and served as an early warning system for potential threats.
Nowadays, only the remains of the wall-ditch complex remain of the once proud horse mine observatory. These remains, together with a group of trees growing on them, were declared a natural monument in 1937. These silent witnesses are a reminder of the historical significance and strategic role that the Pferdebergwarte once played in the defense of Duderstadt.