Watch bison graze on a former chemical weapons plant
Sarin plant to bison prairie
The Rocky Mountain Arsenal covers roughly 16,000 acres on Denver's northeast edge. You drive a loop road through open prairie, with pull-offs, hides and walking trails, and the bison are usually visible from the car.
Why it's unique
The Army built this in 1942 to manufacture chemical weapons, and it went on to produce napalm and sarin. Later Shell leased part of it to make agricultural chemicals. Production stopped in 1982 and the land became one of the most contaminated Superfund sites in the country.
What happened next is the reason to come. Congress designated it a national wildlife refuge in 1992, cleanup ran until 2011, and bison were reintroduced in 2007 from a founding herd of sixteen animals. There are now more than 250, roaming free on ground that was manufacturing nerve agent within living memory, with the Denver skyline visible behind them. More than 330 native species use the refuge.
Before you go
Drive the Wildlife Drive loop rather than parking at the visitor centre and walking. The bison range is fenced and the loop is how you see into it, and animals are most active early and late.
Bring binoculars. The refuge is large and open, and the difference between a good visit and a disappointing one is usually whether you can pick out what is a mile away. It is free.