This tumulus consists of four Neolitihic menhirs originally erected some 5,000–4,500 years ago, each over four meters long and one meter wide. Three menhirs were reused in the Bronze Age around 2,000–1,500 BC as a funerary vault; the fourth is on the ground about ten meters away. Formerly covered with a mound of earth, the site is by its impressive dimensions nicknamed "Tomb of a Giant". According to local tradition, it is the tomb of a giant defeated by the Knights of the Round Table. The Tombeau du Géant was reported as completely destroyed by the 2022 fire, but was in fact saved by firefighters, along with the first few rows of trees surrounding it. Jardin aux Moines The "Garden of Monks", located in Néant-sur-Yvel, also called (), is a megalithic tumulus dating from 5,000 to 4,500 years ago. It is one of the many such mounds present in this region. Natural sites Val sans retour The (), is the most famous tourist place of the forest, located near Tréhorenteuc, west of Paimpont. It is a steep valley dug deep in red shale, the color resulting from the oxidation of the iron ore it contains. During the 19th century, there were two competing locations of the Vale in the forest, the other having been in the near the Tomb of Merlin and also including the initial location of the Tomb of Viviane. In 1896, Félix Bellamy decided that the was the place that inspired the anonymous 13th-century author to write the episode of the Vale in Lancelot-Grail. According to the French tradition of Arthurian legend, Queen Morgan le Fay, half-sister of King Arthur, betrayed by her lover, decided to keep all the unfaithful knights as prisoners in a vale of that name. Only Lancelot, faithful to Queen Guinevere, was able to break the spell, escape, and free the captive knights. High above the Vale, the () is the spot where Morgan le Fay is said to have turned her lover who betrayed her into stone. Another location is the (), a rock overlooking the valley. A lake that since the 1940s has been known as the () marks the entrance to the Vale. Nearby stands the (), a Catholic church featuring imagery of Morgan and other Arthurian characters associated with the Vale reimagined as Christian-themed scenes, painted by two German prisoner-of-war artists after WWII, as commissioned by eccentric local priest