About Marathon Dam

Marathon dam is one of the oldest modern dams in Greece, built in 1929 to provide water for Athens at a time when the city was beginning to expand beyond the capacity of local groundwater and small-scale sources. Located approximately 40 kilometres northeast of Athens on the Marathon River, the reservoir holds only 41 million cubic metres — by far the smallest of the four major Athens water sources. Yet Marathon holds a historical and cultural significance entirely disproportionate to its storage volume. The concrete gravity dam is distinctively faced with Pentelic marble, quarried from the same Hymettus slopes that yielded the white marble used to construct the Parthenon in ancient Athens. This choice of material transformed a utilitarian piece of infrastructure into an architectural landmark of aesthetic merit. The dam sits near the coastal plain of Marathon, home to the ancient Battle of Marathon in 490 BCE where Greek forces famously defeated a Persian invasion — a location saturated with historical meaning that lends additional resonance to the modern engineering works. For the first half of the twentieth century, Marathon was the sole water source for Athens, a responsibility that required careful management during drought years and drove the city's early investment in water infrastructure. As larger reservoirs such as Mornos and Yliki came online, Marathon's role shifted from primary supply to an important secondary source and emergency reserve. Today, the dam functions as a backup component within the integrated Athens water system, contributing volume during wet years and available as a final reserve during acute shortage periods. The marble-faced structure and historic significance have made Marathon a destination for visitors interested in engineering heritage, water history, and the classical archaeology of Attica. In the context of contemporary water scarcity across Greece, Marathon represents both the pioneering efforts of earlier generations to secure Athens's water future and the enduring importance of every available water source in a warming and drying region.