Lunes de Piedra de Riolobos Activity · Riolobos, Valle del Alagón, Cáceres Image of Riolobos, not of the place itself. Pilgrimage (romería) of the "Lunes de Piedra" (Stone Monday) in honor of the Virgen de la Argamasa, held on the second Monday after Easter in Riolobos. Photo: Xemenendura (CC BY-SA 4.0) What to see and do in Riolobos