Assabet River National Wildlife Refuge, (formerly referred to as the U.S. Army's Fort Devens-Sudbury Training Annex), is a 2,230-acre (9.0 km2) protected National Wildlife Refuge located approximately 25 miles (40 km) west of Boston, and 4 miles (6.4 km) west of the Eastern Massachusetts National Wildlife Refuge Complex Headquarters, along the Assabet River. It is located in portions of the Towns of Hudson, Maynard, Stow and Sudbury. The Assabet River National Wildlife Refuge consists of two separate pieces of land. The larger northern section is just north of Hudson Road, extending north to the Assabet River. The southern section is located to the south of Hudson Road. There is a visitor center located in the northern section, on Winterberry Way.