Battery Townsley

Battery Townsley is an underground military complex in the Marin Headlands built with 26 interconnected rooms and reinforced concrete construction. The structure was designed to house and protect heavy gun installations along the coast.

The facility was built between 1938 and 1940 as a defensive coastal position during the Second World War era. It later shifted to scientific research purposes in the 1960s.

The structure represents mid-20th century coastal fortification engineering and serves as an educational center for military defense history.

You can reach the site by hiking a steep trail from the Fort Cronkhite parking area nearby. The location offers guided visits at set times to explore the underground spaces safely.

In the 1960s and 1970s, the facility served as a testing ground for experiments simulating nuclear blast pressure waves. This research work transformed the former gun installation into a scientific research site.

Location: Marin County

Address: Fort Cronkhite, Mill Valley, CA 94941, USA

Opening Hours: Tuesday 10:00-17:30; Thursday 10:00-17:30; Saturday-Sunday 10:00-17:30

Phone: +14153311540

Website: http://nps.gov/goga/historyculture/battery-townsley.htm

GPS coordinates: 37.83586,-122.54350

Latest update: December 9, 2025 20:28