Mile Rock Tunnel

Mile Rock Tunnel is an underground water channel beneath San Francisco that carries stormwater away from several neighborhoods. The system uses concrete pipes that branch under city streets to prevent flooding in densely populated areas.

Construction began in 1914 and was completed in 1915 to protect the rapidly growing city from flooding. The project represents early solutions for drainage in an expanding urban area.

The tunnel represents early twentieth-century municipal engineering solutions for managing urban water systems in rapidly developing San Francisco neighborhoods.

The tunnel is not accessible to regular visitors as it is a critical infrastructure system. You can explore the history and impact of the system by visiting the surrounding neighborhoods it serves.

The tunnel was so narrow that the first official vehicle inspection had to drive in reverse to exit. This unusual experience reveals how cramped the original construction was.

GPS coordinates: 37.77336,-122.50898

Latest update: December 14, 2025 18:10