Nearly two thousand years after Roman engineers built it, the dam at Cornalvo still holds water. It lies in the rolling countryside north-east of Mérida, in Extremadura, and it supplied the Roman city of Augusta Emerita, capital of the province of Lusitania. The dam is an earthen embankment faced with stone, with a tower in the reservoir that controlled the outflow, and it is part of the Archaeological Ensemble of Mérida, a UNESCO World Heritage Site.
The reservoir is surrounded by the Cornalvo Natural Park, a landscape of dehesa, the open woodland of holm oaks and cork oaks typical of Extremadura, where black Iberian pigs root for acorns in autumn and cattle and sheep graze among the trees. The park is home to birds such as storks, eagles and vultures, and in spring the meadows are full of wildflowers. Mérida has another Roman dam, Proserpina, closer to the city, and the aqueducts that carried water to the city, especially the Acueducto de los Milagros, are spectacular.
The riding in this part of Extremadura is relaxed and pleasant. The roads are quiet, with long straights and gentle curves through the dehesa, and traffic is light. The landscape is wide and open, with views over rolling hills dotted with oaks. Summer is very hot, often above forty degrees, so ride early in the morning or late in the afternoon, and carry plenty of water. Spring is the best season, when the fields are green and full of flowers, and autumn is pleasant too.
San Pedro de Mérida and Trujillanos are small villages nearby with basic services, and Mérida, fifteen kilometres away, has fuel, shops and restaurants. Mérida's Roman monuments, including the theatre, the amphitheatre and the bridge over the Guadiana, are among the most impressive in Spain. The local food is excellent: Iberian ham from acorn-fed pigs, torta del Casar, a creamy sheep's cheese, and migas, fried breadcrumbs with pork. A walk along the crest of the dam in the late afternoon, with storks overhead and the dehesa fading into haze, is the most peaceful hour you will spend in Extremadura.