El dolmen de Montelirio Historical milestone · Castilleja de Guzmán, Comarca Metropolitana de Sevilla, Seville The tholos of Montelirio, discovered in 1998 and declared a Bien de Interés Cultural, forms part of the large Chalcolithic settlement of Valencina-Castilleja, dating from around 3000 BC and covering more than 500 hectares. 1998 (descubrimiento); hacia 3000 a.C. (cronología) Photo: Murillo-Barroso M, Peñalver E, Bueno P, Barroso R, de Balbín R, Martinón-Torres M (CC BY 4.0) What to see and do in Castilleja de Guzmán