The last of Vatican City's 'classic' definitive series, issued in 1966, featured bas-reliefs by Rudelli from the pope's bronze chair in the Apostolic Palace's private chapel. (The classic definitive series are those that include a special delivery stamp plus the wartime "Small Medallions" and the 1930s surcharges.) The only other definitives of Paul VI's pontificate, a 1974 series marking the 1975 Holy Year, blurred the lines between definitive and commemorative stamps by mixing the larger size and pictorial nature of commemoratives with a higher print run and range of face values that is more typical of definitives. That trend continues to this day.
Glossary