Masterpiece of Roman hydraulic engineering, it was built with huge blocks of granite stone from Guadarrama, and the method used is called “a hueso”, which means that there is no concrete or mortar between the stones. It holds up due to an ingenious weight balance. Its total length is 14.965 meters. Its arches are 958 meters long. Its highest point reaches 28.10 meters. The total number of arches is 167. The hypothesis of its initial construction points to the 1st century, during the Flavian era, and also to the eras of Nerva or Trajan. The Aqueduct in Segovia (Castile and Leon) is at the top of the list of the best civil engineering works in Spain. Through the ages, it has barely suffered any modifications.