Spanning the diagonal spine of central to northwest Somerville, O | Medford starts off with a ride though Union Square, past Bow Market, then into central Somerville passing the 2021-opened Magoun Square MBTA Green Line station. O then proceeds down Main Street, the commercial heart of northern Somerville, past Royall Park, a US National Historical Site, and across the Mystic River into Medford Center. Excellent riverside bicycle infrastructure flanks the Mystic River, connecting this Line’s terminus with West Medford and with the Wellington and Assembly areas of Medford and Somerville, respectively.