This pair of Neolithic dolmens were thousands of years old when Roman archeologists investigated them. They're on the Causse du Larzac, a limestone plateau housing thousands of Neolithic megaliths.
The Ferrussac dolmens are on the D130 road, only a couple of km east of the village of La Vacquerie-et-St-Martin-de-Castries. The dolmens are only slightly hidden from the road, but an information panel and a small parking area marks the spot of the larger dolmen (the Grand Dolmen of Ferrussac).
The second Ferrussac dolmen is a bit smaller than the first. It's located about 250 m to the southwest of the larger, and 30 m from the road. It takes a bit of looking around to find.
Grand Dolmen, Latitude, Longitude: 43.790200, 3.484100
Petit Dolmen, Latitude, Longitude: 43.789539, 3.482645
This archeological site, called the "Couloir de Ferrussac-Esquirol Dolmen", had three dolmens, a tumulus and a tombe (Tombe de la Trivalle-Ferrussac).
The largest (Grand Dolmen of Ferrussac) contained a large number of artifacts, including weapons, tools, bracelets, fossils and bones, when it was excavated around 1900.
Dolmen-2 (Petit Dolmen of Ferrassac) was empty when discovered, but was imposing enough with its 12-meter diameter and 2-meter height. This dolmen is located 250 m south of Dolmen-1 and 30 m west of the road.
Dolmen-3 was located 250 m north of Dolmen-1 and 150 m west of the road. It's smaller, with an 8-m diameter and 1-m height. We didn't find this one.
Source: Le grand dolmen à couloir de Ferrussac-Esquiol et son site archéologique, by Gaston Combarnous