The U.S. Navy’s “On-The-Roof Gang” was a group of pioneering U.S. Navy and Marine radio operators trained to intercept Imperial Japanese Navy (IJN) radio communications prior to World War II. Their training took place in a specially constructed blockhouse on the roof of the old Main Navy Building in Washington, DC. The graduates of this training became known as the “On-The-Roof Gang” and were posted throughout the Pacific Theater at various intercept stations and aboard ship.