Alongside the 12 stars of the European flag, the stamp shows Michelangelo's drawing of Rome's Campidoglio square, the location of Sala degli Orazi e Curiazi, where the treaty on the European Constitution will be signed.
The background of the stamp is a map of Europe in three colours -- sky blue for the 25 European Union member countries, dark blue for Turkey, Bulgaria, and Romania, and blue-green for Croatia.
Sala degli Orazi e Curiazi is where on 25 March 1957 Belgium, France, Germany, Italy, Luxembourg, and the Netherlands signed the Treaty of Rome, which established the European Economic Community.
The stamp will be worth 62 cents -- the cost of an Italian stamp for letters sent to countries in Europe.