Cukur Fountain

The Čukur Fountain is a monument built to commemorate the Čukur Fountain incident of 15 June 1862, starting with the death of a boy -- Savo Petković -- and growing into a conflict between Serbia and the Ottoman Empire. After a quarrel at a fountain, the Serbian and Turkish police came to shoot at each other, after which a riot broke out in the town that lasted the night. The following day, a truce was agreed and the Ottoman police was ordered to leave the Belgrade Fortress, with safe passage guaranteed by the Serbian government.

Source: Wikipedia