May 31, 1578: Italian archaeologist Antonio Bosio discovers the Christian catacombs in Rome. Some have mistaken them for places of refuge or worship, but Christians used them mainly as burial chambers.

May 31, 1638: Puritan pastor Thomas Hooker arrives in what is now Connecticut, after leaving Massachusetts because of a rivalry with Roger Williams. The minister also helped organize America's first federal government, the United Colonies of New England (see issue 41: The American Puritans).

May 31, ...