Karl Marx was born on May 5, 1818, in the southern German town of Trier (at the time Trier was in the Kingdom of Prussia). To celebrate the bicentennial of his birthday, the town issued a souvenir zero euro bill, that proved to be very popular. (I am tempted to buy one on E-bay).
I also need to brush up on my understanding of Marxism. The Wikipedia entry is probably a good start: Marxism holds that human societies develop through class struggle. In capitalism, this manifests itself in the conflict between the ruling classes (known as the bourgeoisie) that control the means of production and the working classes (known as the proletariat) that enable these means by selling their labor power in return for wages. .. Marx predicted that, like previous socio-economic systems, capitalism produced internal tensions which would lead to its self-destruction and replacement by a new system: socialism.
Here in the United States socialism is a toxic word, but man! since the 1980s, the forces of capitalism have resulted in a very unequal sharing of prosperity (no real wage increases for middle class worker, and spectacular riches for the one-percenters at the top). Something will have to give.