Burial mounds and cromlech of Ribas de Sil Nature · Ribas de Sil, Quiroga, Lugo Image of Ribas de Sil, not of the place itself. As well as several Neolithic mámoas, the concello preserves a cromlech, a circle of set stones that is a rare type of monument in Galicia and very infrequent in the interior of Lugo. Photo: OlgaS01 (CC BY-SA 4.0) What to see and do in Ribas de Sil