I did not know that in 2004 the EU granted its member nations the privilege of minting commemorative coins for circulation (like our American 50 state quarters). Ordinarily, Vatican City places the bust of the current pope on its coins. But 100,000 of a special issue are permitted to be minted each year in the 2 Euro denimination. In 2005, a recognition of World Youth Day was included on the reverse side. (All EU nations have the same design on the obverse or front.)
Although Vatican City is not a member of the EU, it does mint its coins according to the new European system.