Granite, cut and stacked
Look closely at the piers and you will find no mortar between the blocks. The builders laid large granite blocks a hueso, as the Spanish say, “to the bone”, that is, dry, stone on stone. What holds them is shape and weight. In each arch, the wedge-shaped blocks press against each other, so the load from above squeezes the ring shut; the piers below are tall stacks of stone, pressed down by everything above them.
The arcade is 959 metres long, with 167 arches. At the Plaza del Azoguejo, where the ground is lowest, it rises on two tiers to 28.10 metres, about the height of a nine-storey building.
How the water came in
The arches are only the end of the story. The whole aqueduct is 16,186 metres long, from its source in the Guadarrama mountains to the city. Like other Roman aqueducts, it worked by gravity, and the arcade is the stretch where the channel had to cross the valley in front of the old town. On the way, the water passed through two settling tanks, the Casita de Piedra (also called the Chamberí sand trap) and the San Gabriel sand trap, where it slowed down and dropped its sand before going on. The aqueduct kept supplying Segovia until the last third of the twentieth century.
When was it built? The date keeps moving
You will read very different dates for the aqueduct, and they come from official sources. The UNESCO page for the Old Town of Segovia says “probably built c. A.D. 50” in its summary, and in another paragraph gives “c. 50 BC”, a century earlier. Segovia’s own tourism office places the building in the early second century CE, under Trajan, and its history page narrows it to “after 112 AD”, at the end of Trajan’s reign or under Hadrian. Until the question is settled, “early second century” is the date the city itself uses, and the one used here.
Its later history is better documented. The first written mention is in a document of Segovia Cathedral from 1201, and one of the earliest images of it appears in Cantiga 107 of Alfonso X the Wise, written around 1280.
Segovia or the Pont du Gard?
The two are often compared, and they are very different experiences. The Pont du Gard is taller (nearly 49 metres) and stands alone over a river in open country. The aqueduct of Segovia runs straight through a city, and you can stand right under the arches in a busy square. Both use the same structural idea, stones cut so precisely that each keystone and voussoir locks the arch by its own weight.
Where to see it
The aqueduct is in the open, free to see, and crosses the Plaza del Azoguejo at the entrance to the old town of Segovia. The Old Town of Segovia and its Aqueduct have been a UNESCO World Heritage Site since 1985.
Sources
- Turismo de Segovia, “Aqueduct” and “History of the aqueduct”.
- UNESCO World Heritage Centre, “Old Town of Segovia and its Aqueduct” (311).
