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.
The sections in two tiers are 115" high. A raised section of stonework in the center once had an inscription. Today only the holes for the bronze letters survive. Steps at the side lead up to the old city walls (at left).
Detail showing holes used to lift rocks up with calipers