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Proserpina
About
The Proserpina Dam held back a reservoir north of Emerita Augusta, an earthen embankment fronted by stone buttresses that still stretches 427 meters across the valley. Water released from its sluices fed the Aqueduct of the Miracles into the city below. Roman engineers built it in the first or second century CE alongside the nearby Cornalvo dam, and it has never stopped holding water since. Local swimmers still use its reservoir as a summer bathing spot today.
What happened here
Built to hold water for a town, a farm or a mine, and shaped by what the local rock allows: a straight wall of masonry backed with earth, or a curved one where the gorge is narrow. The core is concrete and rubble, faced in cut stone, and the upstream face is often waterproofed with mortar. Water is drawn from a tower with sluices at different heights, so the supply keeps running as the level drops and the silt stays at the bottom. Overflow channels carry the winter flood past the wall rather than over it — the detail that decides whether a dam survives. Silt is the long enemy; a reservoir has a working life and everybody involved knows it.
Sources
Roman Maps shows the empire frozen at 11 August 117 CE, the day Trajan died — its moment of greatest territorial extent. Explore the full map →