The Fort Devens-Sudbury Training Annex was a former annex of Fort Devens that was operational from 1942 to the 1990s. It originally opened as an ammunition dump for the base, and old railroad lines and bunkers can still be seen in the area. It then functioned as a dumping ground for the Natick Laboratories until the 1980s. In the 1990s, the site was cleaned up and turned into the Assabet River National Wildlife Refuge.