Bet you didn't know that the Order of Malta (the Knights of the...St John...Order...Malta...something) is a sovereign entity. They have embassies. They go to international conferences. They are recognised as sovereign by rather a lot of states. I think they took Malta in the 1500s after the Turks were chased off (probably not by them) and then were chased off in turn by Napoleon and have since made ineffectual attempts to regain some territory. They have a few buildings in Rome and do good works.

All that courtesy of Krasner, Sovereignty: Organized Hypocrisy, which is an entire book saying that states follow the rules they want to follow. IR people have the most interesting topics -- and the most boring things to say about them. Why?