Pontón de la Oliva

Pontón de la Oliva is a limestone dam across the Lozoya River near Patones, built as an important water infrastructure project. The structure rises prominently from the riverbed and creates a reservoir basin within the surrounding valleys.

Construction began in the 1850s as Madrid's first major water infrastructure undertaking, involving thousands of workers who labored on the riverbank. This project represented a significant turning point in how the region managed its water resources and urban development.

The dam structure contains marine fossils within its stones, reflecting the geological history of the region when it was submerged underwater millions of years ago.

You can walk on the dam structure and hike on trails throughout the surrounding area, with parking available near the M-134 road access. The terrain varies, so wear appropriate footwear and bring water, especially on warmer days.

Water seeped through the limestone base faster than engineers expected, causing the dam to lose its effectiveness after only a few decades. This early failure reveals how difficult it was to build such structures with the knowledge and tools available at that time.