Looking for a good pub quiz question? This one might catch some people out. Europe has a surprising number of monarchies, ranging from the well known to the obscure. They cover the spectrum from constitutional monarch through power sharing to absolute ruler. The youngest monarchy was instituted in 1929 (and that's a clue).
Among the dwarf states of Europe, the Principality of Andorra is the largest. Until quite recently, it was an absolute monarchy. It was governed not by one, but two princes, and both are not citizens of Andorra. They don't even live in Andorra. To make the case even more curious, it is not a hereditary monarchy.