Embalse y presa romana de Proserpina Monument · Mérida, Tierra de Mérida - Vegas Bajas, Badajoz A dam of Roman origin (specialists debate whether the entire current structure is from a single phase or was expanded in the 2nd century AD) that holds back about 6.5 hm³ over some 70 ha; it supplied water to Emerita Augusta through the Los Milagros aqueduct. Declared a Monumento Nacional in 1912, it is today also an area for swimming and hiking, with a perimeter trail of about 6 km. Photo: Alonso de Mendoza (CC BY-SA 4.0) What to see and do in Mérida