San Lazaro Aqueduct, Rabo de Buey, Merida, Spain, 2007 (photo)

The Rabo de Buey Aqueduct (also known as Las Tomas or Las Thomas) was one of the three conduits that supplied water to the Roman city of Emerita Augusta. The main arcade structure was over 16 meters high, constructed in dry-stone with half barrel vaults. The wide expanse of the Albarregas Valley was overcome by the construction of elevated arches which linked the channel's supporting pillars. The channel itself (specus) was 60 centimeters wide and lined by a layer of hydraulic mortar. Beneath the aqueduct stretched the road which united the Roman city Emerita Augusta (later Merida) with Toletum (modern Toledo) and Corduba (modern Cordoba). In the 16th century the new San Lazaro aqueduct-bridge was built, using many ashlars from its Roman aqueduct. From the original structure only three supporting pillars with two of their union arches remain. The entire length of the aqueduct was repaired at the end of the 19th century, and water continued to flow in it to the city until the end of the 1970s.