An Iberian settlement preceded Roman Segobriga, which was supplied by the famous aqueduct 'El Puente', with 166 arches. Begun in the 1st century AD under Emperor Domitian and probably completed under Trajan in the early 2nd century, the aqueduct brought water to Segovia from the Frío River 10 miles (16 km) away. At its highest point, the water channel is 100 feet off the ground. The visible part of the great structure consists of 800 meters of granite blocks, 166 arches, 120 pillars. The aqueduct is still in use.