Red Gate Woods, located in the Palos Preserves in the southwest suburbs, features a picnic grove and is the home of the world’s first nuclear reactor. The site includes some of the more than 42 miles of trails in the Palos Trail System, the second longest system throughout the Forest Preserves, providing unique opportunities for walks and rides on single-track and unpaved trails.

On this page:

• Location & Things to Do
• Trails
• Nature Notes
• “Site A” & The World’s First Nuclear Reactor

Location & Things to Do

Trails

Nature Notes

Red Gate Woods is primarily made up of oak woodlands, along with savanna, forested ravines, freshwater marsh, ephemeral creeks and small prairie pockets. The preserve is home to 116 birds and 253 native plants with more plants expected to be revealed with restoration work.

Red Gate Woods also sits on Mount Forest Island, the triangle-shaped area which used to be an actual island when glaciers melted around 12,000 years ago.

Beginning in the winter of 2023, the Forest Preserves began undertaking large-scale restoration efforts at Red Gate Woods.

“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.