10 Euros

Robert Kalina won the internal ECB design competition in 1996 with a deliberately anonymous brief: no real monuments, no identifiable people, no specific national geography. The bridges and windows on the euro series are composites — architecturally plausible but fictitious, a political necessity given that any real building would privilege one member state over others. For the 2002 launch, De La Rue, Giesecke & Devrient, and several national printers produced notes simultaneously, with each country's output identifiable by a letter prefix in the serial number.

The letter "X" denotes Germany, "Y" Greece — a detail that briefly mattered when euro-skeptic commentators tried to track which countries' notes were circulating where.