Porte de Hal
Although modified, the Halle Gate is the last remnant of the second walls of Brussels. Their course can be seen by the current Small Ring, although it stops short of the Halle Gate, and they still define downtown Brussels, often called the "Pentagon". In the 1950s, with pressure from the automobile, new plans to improve traffic flow were implemented, partly due to the 1958 World's Fair. Later tunnels were dug, and one of the main lines of the Brussels metro now runs primarily underneath the small ring. Today, the small ring is a major arterial ring road.