Beni Hammad Fort, also called Al Qal'a of Beni Hammad, is a fortified palatine city located in the Hodna Mountains northeast of M'Sila. The fortress was built in 1007 AD by Hammad ibn Buluggin and became later the first capital of the Hammadid dynasty in 1017 AD. Beni Hammad Fort was inscribed as a UNESCO World Heritage Site in 1980.
The Qal'a (Fortress) is located in a mountainous setting at more than 1,000 m altitude. In the 11th century, a prosperous Islamic town developed here. Surrounded by walls, it includes residential complexes, a large mosque, and the emir's palace surrounded by gardens and pavilions. Its design later influenced Arab architecture as can be seen in the Maghreb, Andalusia and Sicily.
The Hammadid mosque is said to have been the largest mosque constructed in North Africa prior to the twentieth century and it features the typical Maghreb style square minaret. The minaret, 82 feet (25 m) in height, is the only remaining part of the ruined Great Mosque.
Excavations have brought to light numerous terracotta, jewels, coins and ceramics testifying to the high level of civilization under the Hammadid dynasty. Also among the artifacts discovered are several decorative fountains using the lion as a motif.
In the Qal'at Beni Hammad fragments of stucco were discovered from the Qasr al-Salam and the Qasr al-Manar which may be the oldest fragments of muqarnas (ornamented vaulting) in the Western Islamic world, dating back to the 11th or 12th century. The framework of a marble basin and a grey marble fragment document the use of multifoil arches with spiral-form impost decoration. The use of this motif at the Qal'at subsequently spread during the times of the Almoravids and became universal in Almohad buildings. The square rooms surrounded by rampant barrel vaults in the Qasr al-Manar have been compared to the Almohad minarets and the Torre Pisana in Palermo which it predates. The Hammadid palaces are also noted to contain the first or one of the first documented use of shadirwan (a fountain in a courtyard).
Excavations began in 1908, resumed from 1952-1956 and continue to this day as most of the site remains unexplored and the aspects of the palaces await further study.
https://whc.unesco.org/en/list/102/
https://en.wikipedia.org/wiki/Qal'at_Bani_Hammad
The cache
See the minaret tower at the posted coordinates and count the narrow windows (on all sides).
The number is X.
You will find the cache here:
N 35° 50.(X56-X*X-100) E 004° 48.(X13+X*X-100)
The final is placed on the scenic road towards Bordj Ghedir, at a place with marvellous views.