Red Gate Woods

signs explaining Site A, burial place of the world's first nuclear reactor
Visitors to Red Gate Woods can visit Site A, burial place of the world's first nuclear reactor.

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Location & Things to Do

Red Gate Woods


S Archer Ave, northeast of 107th St
Cook County, IL 60480
(near Willow Springs)

Things to Do & Amenities

  1. Portable bathroom open May 1 to October 31 depending on weather conditions.

Picnic Groves

  • Accessible Grove #1
    (with shelter)
    • Accessible May 1 to October 31.
    • Distance to parking: 210 ft
    • Distance to accessible portable bathroom: 205 ft
    • Capacity: 300 people
Event Permits PageGrove PDF Map of Red Gate Woods


Year-round: Sunrise to Sunset

Closures & Alerts


Palos Trail System

The extensive and varied Palos Trail System winds through rolling hills and deep ravines, providing beautiful views of the surrounding landscapes.

Location: Hickory Hills, Justice, Palos Hills & Willow Springs



Estimated Total Length

42.1 miles


Year-round: Sunrise to Sunset

Closures & Alerts

*Please be a courteous trail user: Follow posted signs and our trail rules and etiquette.

Scientists at Site A Commemorative Boulder
Scientists at Site A Commemorative Boulder.

“Site A” & The World’s First Nuclear Reactor

On December 2, 1942, scientists at the University of Chicago produced the first controlled nuclear chain reaction in human history. Soon after, the nuclear reactor was relocated to “Site A” on land leased from the  Forest Preserve District of Cook County in Red Gate Woods. The US Army Corps of Engineers built a research facility and an additional reactor as part of the Manhattan Project, the U.S. nuclear development program during World War II.

In addition to research labs and reactor control rooms, the complex included a guard house, dog shelter, library, cafeteria, dormitory, and recreational spaces. The scientists who lived and worked there throughout World War II maintained a strict code of silence, as their discoveries were critical for the success of the U.S. military’s atomic program

When Site A closed in 1954, the two reactors were buried and a decades-long environmental cleanup and monitoring effort began. In 1991, after extensive clean-up by the department of energy, the area was re-opened for safe public recreation. Today, Red Gate Woods remains the burial site of the world’s first nuclear reactors – marvels of science that ushered America into the Atomic Age.