The Aqueduct of Segovia (or more precisely, the aqueduct bridge) is a Roman aqueduct and one of the most significant and best-preserved ancient monuments left on the Iberian Peninsula. It is the foremost symbol of Segovia, as evidenced by its presence on the city's coat of arms.The aqueduct transports waters from Fuente Fría river, situated in the nearby mountains, some 17 km (11 mi) from the city in a region known as La Acebeda. It runs another 15 km (9.3 mi) before arriving in the city.
The water is first gathered in a tank known as El Caserón (or Big House), and is then led through a channel to a second tower known as the Casa de Aguas (or Waterhouse). There it is naturally decanted and sand settles out before the water continues its route. Next the water travels 728 m (796 yd) on a one-percent grade until it is high upon the Postigo, a rocky outcropping on which the old city center, the Segovia Alcázar, was built. Then, at Plaza de Díaz Sanz (Díaz Sanz Square), the structure makes an abrupt turn and heads toward Plaza Azoguejo (Azoguejo Square). It is there the monument begins to display its full splendor. At its tallest, the aqueduct reaches a height of 28.5 m (93 ft 6 in), including nearly 6 m (19 ft 8 in) of foundation. There are both single and double arches supported by pillars. From the point the aqueduct enters the city until it reaches Plaza de Díaz Sanz, it boasts 75 single arches and 44 double arches (or 88 arches when counted individually), followed by four single arches, totalling 167 arches in all.
The construction of the aqueduct follows the principles laid out by Vitruvius as he describes in his De Architectura published in the mid-first century.
The aqueduct is the city's most important architectural landmark. It had been kept functioning throughout the centuries and preserved in excellent condition. It provided water to Segovia, mainly to the Segovia Alcázar, until recently. Because of differential decay of stone blocks, water leakage from the upper viaduct, and pollution that caused the granite ashlar masonry to deteriorate and crack, the site was listed in the 2006 World Monuments Watch by the World Monuments Fund. Contrary to popular belief, vibrations caused by traffic that used to pass under the arches did not affect the aqueduct due to its great mass. WMF Spain brought together the Ministry of Culture, the regional government of Castilla y León, and other local institutions to collaborate in implementing the project, and provided assistance through the global financial services company American Express.