In the evolution of quarantine, Malta (pictured) stands out for its importance in the late 1700s and 1800s. "It was used by the British as a kind of outsourced border to defend against the threat of cholera in particular," says Manaugh. "If you were headed to the U.K. by ship from the Mediterranean, rather than quarantine in Britain, you would do your quarantine in Malta, meaning that your actual, physical entry into the U.K. would be as frictionless as possible."