Raven, perched on a cannon at the Tower of London. Legend has it that if the ravens ("Corvus corax") should leave the tower, then the tower will fall. Charles II ordered that the Constable of the Tower shall ensure that there are always at least six ravens at the tower. The cannon, probably a 24 lb piece of Flemish artillery, dates to about 1607 and brought to England from Malta in about 1800. The carriage (not visible in the picture) was manufactured in 1827. The White Tower is visible in the background.