Fort Devens is a United States Army Reserve military installation in the towns of Ayer and Shirley, in Middlesex County and Harvard in Worcester County in the U.S. state of Massachusetts. Due to extensive environmental contamination it was listed as a superfund site in 1989. Although closed in 1996, it was reopened the next day as the Devens Reserve Forces Training Area, located in Lancaster. The name reverted to Fort Devens in May 2007.