When completed in 1904, the East Boston Streetcar Tunnel from State Street, Boston, to Maverick Square provided the first nonferry connection between East Boston and the central city. An engineering marvel, it was the largest diameter and longest submarine railroad tunnel in the world, eclipsing its models in London and New York. Boston Transit Commission engineer Howard Carter used fresh concrete here for the first time in tunnel construction. A forty-five-foot-square duct in the roof of the tunnel connected to ventilating towers at both ends. As usage increased, the streetcars were replaced by third rail subway service in 1924; in 1952, the Blue Line was extended to Wonderland and the original Maverick Square station was replaced.