end of 1st to early 2nd century CE (but no date is recorded in Roman sources)

One of the greatest surviving monuments of Roman engineering, this aqueduct stretches from the walls of the old town to the edges of Sierra de Guadarrama. It is about 2950 feet long although the section where the arches are divided in two levels is about 900 feet. It is made of rough-hewn massive granite blocks, joined without mortar or clamps.