The Assabet River Rail Trail (ARRT) is a partially-completed multi-use rail trail running through the cities and towns of Marlborough, Hudson, Stow, Maynard, and Acton, Massachusetts. The 5.4-mile point-to-point trail is generally considered an easy route. The trail surface is paved asphalt, smooth, and typically at least 6 feet wide. The Marlborough section plunges into woods with a shady canopy, passes beneath MA 85, crosses wetlands around Flagg Brook serving as a wildlife corridor, and offers views of the Fort Meadow Reservoir from an overlook with benches. The trail is a conversion of the aband oned Marlborough Branch of the Fitchburg Railroad.