The first Serbian postage stamps were issued on 1 July 1866 (13 July 1866 according to the new calendar). These stamps, featuring the image of Serbian Prince Michael, popularly known as the “Vienna printing” (printed at the Imperial State Printing House in Vienna), were supposed to be released into circulation on 1 May 1866, but due to an (un)intentional delay, they were printed two months later. As a collector’s item, they represent a rarity and a true gem of Serbian philately, in the broadest sense of the word.