Azud del acueducto romano de Segovia

The azud is the Roman intake weir that captured spring water from the Sierra de Fuenfría and fed it into the 17-kilometre channel supplying Segovia's famous aqueduct. Built around 200 AD at the height of the Roman Empire, the full water system — weir, channel, and arcade — is among the best-preserved examples of ancient civil engineering anywhere in Europe and holds Historic Civil Engineering Landmark status. The weir itself is the least-visited but hydraulically critical node of the network: without it, the iconic arched arcade in the city centre could never have functioned. Sitting as an archaeological site away from the main tourist flow, it offers a quieter vantage point for understanding the precision Roman engineers brought to large-scale urban water supply.