Segovia Aqueduct: How Roman Builders Made 24,000 Granite Blocks Stand Without Mortar

Segovia's Roman aqueduct turns a simple material—granite—into a self-supporting waterway. Roughly 24,000 blocks were stacked without mortar, and the surviving arcade rises about 28 metres above the city. 1

The arches were assembled over timber frames. Workers placed wedge-shaped stones around each frame and locked the arch with a carefully carved keystone. They used iron lifting tongs, oak rollers, treadwheel cranes, hemp ropes, pulleys, and water-swollen wooden wedges to cut and move the granite. 2

The two-tier arcade is one of Europe's most intact Roman aqueducts, and its dry stone blocks remain held together by compression. 3

Visuals include photographs by Bernard Gagnon, licensed under CC BY-SA 3.0: Aqueduct of Segovia 01, 08, 02, and 06.