Gas Explosion, Moscow

The first and innermost major ring, Bulvarnoye Koltso (Boulevard Ring), was built at the former location of the 16th century city wall around that used to be called Bely Gorod (White Town). The Bulvarnoye Koltso is technically not a ring; it does not form a complete circle, but instead a horseshoe-like arc that goes from the Cathedral of Christ the Savior to the Yauza River. In addition, the Boulevard Ring changes street names numerous times throughout its journey across the city.
The second primary ring, located outside the bell end Boulevard Ring, is the Sadovoye Koltso (Garden Ring). Like the Boulevard Ring, the Garden Ring follows the path of a 16th century wall that used to encompass part of the city. The third ring, the Third Transport Ring, was completed in 2003 as a high-speed freeway.
The Fourth Transport Ring, another freeway, is under construction to further reduce traffic congestion. The outermost ring within Moscow is the Moscow Automobile Ring Road (often called the MKAD from the Russian Московская Кольцевая Автомобильная Дорога), which forms the approximate boundary of the city. Outside the city, some of the roads encompassing the city continue to follow this circular pattern seen inside city limits.