Moscow is situated on the banks of the Moskva River, which flows for just over five hundred kilometers through western Russia, in the center of the East-European plain. There are 49 bridges across Moskva River and its canals within city limits.
Moscow's road system is centered roughly around the heart of the city, the Moscow Kremlin. From there, the roads in general radiate out to intersect with a sequence of circular roads or "rings" focused at the Kremlin.
The first and innermost major ring, Bulvarnoye Koltso (Boulevard Ring), was built at the former location of the sixteenth century city wall around what 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 Saviour 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 Boulevard Ring, is the Sadovoye Koltso (Garden Ring). Like the Boulevard Ring, the Garden Ring follows the path of a sixteenth 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 currently 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.