Zero Euro Souvenir Banknote - Karl Marx

The German city of Trier has been selling thousands of zero-euro souvenir bank notes recently to celebrate the 200th birthday of Karl Marx on May 5.

The bills have drawn a sizable number of buyers around the world. The first batch of 5,000 notes were sold out after going on sale, and the city is now printing 20,000 more.

The bank notes, printed in purple, look like genuine euros but are labeled "souvenir."