M | Arlington begins with a journey through Inman Square, where new sidewalk-level bicycling lanes have been installed alongside a bustling café and restaurant scene. Proceeding approximately a mile down Beacon Street on mostly protected bike lane, the line leads through Porter Square, then along Massachusetts Avenue until reaching the Fitchburg Cutoff Path, part of a series of paths providing a contiguous, traffic-separated route from Boston to Bedford and Concord. The line then ends approximately two miles past Alewife Station, along the Minuteman Bikeway, in Arlington Center.