Belgrade fall among the mostly demolished and renewed cities. In the area of the Kalemegdan Fortress even today we can see cannon balls of various types. Since cannons were invented in the 14th century, thousands of stone and then iron balls, with or without gunpowder charge, fell on Belgrade. In 1862, the Turks were bombarding the city from within the fortress for four and a half hours; 357 buildings were demolished, and one ball went through a bell tower of the Cathedral. In the First World War, in October 1915, Belgrade was under a cannonade 30,000 grenades. The most severe destruction was by the Nazi aviation on 6 April 1941, marking the beginning of the Hitler’s attack on Yugoslavia in the Second World War. The Operation Punishment killed  almost 4,000 people of Belgrade, and the demolition of the National Library destroyed numerous valuable mediaeval manuscripts, thus inflicting an invaluable loss. If something like that could have been expected from the Germans, we still cannot explain the motives of the Allied bombardment of Belgrade, four times in the period between April and September 1944. The first Anglo-American air raid  was on Easter on 16 and i 17 April. Once again, many people died. Other Serbian cities were bombarded, as well. The most recent air raids Belgrade and its inhabitants, as well as those all over Serbia, experienced under the NATO aviation bombardment, which lasted from March to June 1999. Even today its effects are visible in Belgrade. April is certainly a bad month for Belgrade – an air raid on 16 April, hitting the RTS (Serbian radio and TV Station), 16 employees got killed, as they had not been evacuated in time. As in 1944, in 1999, too, unexploded grenades were found with the words written on them, “Happy Easter