Two female suicide bombers killed dozens pf people on two packed Moscow metro trains in the morning rush hour on Monday, officials said.
The current death toll makes it the worst attack on Moscow since Feb. 2004, when a suicide bombing killed at least 39 people on a metro train.
Here are some details about Moscow's metro system, which ws one of the greatest prestige projects of dictator Josef Stalin. Many of the stations in the city centre are built in palatial style, with marble-clad walls, frescoes, mosaics, chandeliers and statues, many lauding the 1917 Bolshevik revolution:
BEGINNINGS:
-- Construction of the Moscow Metro began in the 1930s. The first line opened in May 1935 between Sokolniki and Park Kultury with a branch to Smolenskaya which reached Kievskaya in April 1937.
-- Construction continued throughout the 1930s and throughout World War Two. As Moscow was besieged in late 1941, the metro stations were used as air-raid shelters.
-- The Council of Ministers moved its offices to the platforms of Mayakovskaya station, where Stalin made several public speeches.
-- The Koltsevaya (ring) Line was planned first as a line running under the Garden Ring, a wide avenue surrounding the border of Moscow's city centre. The first part of the line - from Park Kultury to Kurskaya (1950) - follows this avenue, but the rest of the ring line was modified to connect to nine intercity train stations in Moscow.
THE 1950s:
-- The stations on the Arbatsky (or Arbat) line, constructed during the Cold War, were planned as shelters in the event of nuclear war with the United States.
-- During the late 1950s, the architectural extravagance of new metro stations was significantly reduced, under the orders of Nikita Khrushchev.
-- He championed a more simple or standard layout, which quickly became known as "Sorokonozhka" or "Centipede" due to the columns aligned in rows down either side of the platform.
-- During this period, stations differed from one another only in the colour and design of tiles used. Most of these stations were poorly built.
RECENT DEVELOPMENTS:
-- In the mid-1970s, architectural extravagance was restored, and original designs once again became popular.
-- Construction of new stations continues to this day, as does restoration of the original stations, such as Mayakovskaya.
DESIGN:
-- The marble used in the Moscow Metro was brought from all over the former Soviet Union from places including the Ural Mountains, Altay, Central Asia and the Caucasus.
-- Black marble from the Urals, Armenia and Georgia decorates the walls of the Byelorusskaya, Ploshchad Revolutsii, Elektrozavodskaya and Aeroport stations. Deep-red marble from Georgia adorns the Krasnye Vorota metro station.
SOME NUMBERS:
-- The Moscow Metro has 298.8 km of route length, 12 lines and 180 stations; on a normal weekday it carries over 7 million passengers.
-- In Aug. 2009 Moscow unveiled a refurbished metro station decorated with an inscription heaping praise on Stalin, sparking outrage from opposition and human rights groups.
-- The chandeliered, mosaic-covered vestibule in central Moscow's Kurskaya station bears a line from an old version of the Soviet national anthem: "Stalin brought us up to be loyal to the nation, inspired us to labour and great deeds."
ATTACK:
-- The first known attack inside the Metro came during the time of Leonid Brezhnev, when a bomb planted in a carriage in Jan. 1977 by Armenian separatists killed seven people and injured another 37.