The Aqueduct of Segovia was built under Roman rule to bring water from the Sierra de Guadarrama to a settlement on a rocky ridge. Its exact date remains debated, but construction is generally placed in the later first or early second century CE, not securely in one emperor's reign. Water traveled from the Frío River area through a long channel that settled impurities, followed contours, and approached the town. The celebrated arcade solved only the final topographic problem, carrying the conduit across a deep depression before water entered an urban distribution system.

The monumental visible section uses thousands of granite blocks set without mortar. Piers and arches rise in two tiers near the present Plaza del Azoguejo, where the structure reaches its greatest height. Careful cutting, weight, proportion, and compression hold the masonry together, while the upper channel once carried flowing water. The design was practical civil engineering and an assertion of Roman urban order. It supplied baths, fountains, houses, and public life, though later repairs changed portions of the channel and the precise layout of ancient distribution remains a subject of study.

Unlike many Roman aqueducts, Segovia's system continued serving the city through medieval and early modern centuries. A section was damaged during Muslim-Christian warfare in the eleventh century. Repairs associated with the Catholic Monarchs in the late fifteenth century reconstructed missing arches, reportedly under Fray Juan de Escobedo, while respecting the ancient form. Niches above the central arcade once carried Roman inscriptions and later received Christian images. These changes show active civic reuse rather than uninterrupted survival in pristine condition. Water continued passing through the aqueduct into the modern era.

Urban growth, vehicle vibration, pollution, water infiltration, and weathering created new threats in the nineteenth and twentieth centuries. Conservation campaigns stabilized blocks, repaired the channel, restricted traffic beneath vulnerable sections, and studied salt and biological damage. The modern water supply eventually replaced the ancient function, ending stresses created by leakage but also changing the monument from infrastructure into heritage. Some stones and arches are replacements, yet most of the elevated Roman fabric survives in its original alignment and structural system. The longer buried and ground-level route is less visually dramatic but essential to understanding the work.

UNESCO inscribed the Old Town of Segovia and its Aqueduct in 1985. The arcade remains freely visible within active streets and squares, while interpretation extends to the water catchment and channel beyond the famous city-center span. Its authenticity lies in extensive Roman granite construction, engineering logic, and continued relationship with Segovia, not in absolute material purity. Municipal and heritage authorities manage conservation, monitoring, and the effects of urban use. The aqueduct's history is remarkable because a utilitarian water system became a civic emblem without losing the physical evidence of ancient design, medieval repair, and modern preservation.