This unique artillery piece was cast at the Moscow Cannon Foundary in 1586 and is a bronze cannon more than five meters long with a calibre of 890 millimetres, This gigantic weapon weighs more than 39 tons. Since 1960 it has stood on a gun-carriage in Ivanovskaya Square surrounded by vast cast-iron cannon balls, each of which weighs about a thousand kilos. The cannon balls are purely decorative, as the Tsar Cannon has never been used in military action, although it was originally intended as a powerful weapon in the Kremlin's defences.