North Station (underground concourses linking rail, subway, and arena)

North Station's terminal complex includes underground concourses and platforms that interconnect commuter rail lines, MBTA subway services, and the TD Garden arena. Pedestrian tunnels and lower‑level passageways beneath Causeway Street and adjacent blocks enable transfers between transit modes and provide access to arena event entrances. The station's subterranean elements are a primary intermodal hub for Boston's north‑side transport and event circulation. North Station's underground infrastructure has been modified over time to accommodate changes in rail and arena operations.