High Quality Content by WIKIPEDIA articles! The Blackwall Tunnel is a pair of road tunnels underneath the River Thames in east London, linking the London Borough of Tower Hamlets with the London Borough of Greenwich, and part of the A102 road. The northern portal lies just south of the East India Dock Road (A13) in Blackwall;A the southern entrances are just south of The O2 (formerly the Millennium Dome) on the Greenwich Peninsula.B Before the opening of the Dartford Tunnel in 1963, the Blackwall Tunnel was the easternmost Thames crossing for vehicles, excluding ferries.