Imagine a passport, coins and postage stamps issued by a sovereign nation that possesses zero square miles of territory. The Sovereign Military Order of Malta operates out of two buildings in Rome, holds diplomatic relations with over 114 states, has permanent observer status at the United Nations, and runs a humanitarian network of around 52,000 medical professionals and 100,000 volunteers in more than 120 countries.

This episode traces how a hospital founded in Jerusalem around 1048 became an independent order under a 1113 papal bull, took up arms as the Knights Hospitaller, ruled Rhodes and then Malta as a naval power, and lost everything to Napoleon in 1798 before finding shelter under a Russian tsar. It examines the legal debate over whether sovereignty requires land, the 1953 Vatican ruling defining the order's sovereignty as function ...