It’s October 27, 1962, the apex of the Cuban Missile Crisis. In response to a U.S. destroyer’s depth charges, a Soviet submarine fires a nuclear torpedo, destroying a U.S. aircraft carrier. Two American destroyers counterattack and air strikes are ordered on the Soviet missile bases in Cuba. The Soviet commander on the island uses his tactical nuclear weapons and kills an entire marine division at the U.S. base at Guantanamo Bay. At 4:18 p.m., an SS-4 missile is fired at Washington from the Soviet base at San Cristobal. Less than fifteen minutes later its warhead detonates 2,000 feet above the Lincoln Memorial. The radius of total destruction from the blast is 1.5 miles. The Kennedys, Lyndon Johnson, the U.S. brass are all dead. So are 250,000 Washingtonians. In Omaha, the Strategic Air Command implements the Single Integrated Operational Plan, the comprehensive blueprint for launching an attack on the Soviet Union and its allies. While Soviet submarines are able to fire off two more nuclear weapons, 950 American nuclear bombs rain down on the U.S.S.R. The United States emerges intact, but the Soviet Union is destroyed, its government gone and nearly its entire populationd dead or dying from starvation or radiation poisoning. No part of the world escapes the the effects of fallout: China and India suffer famine and Europe and North America face food shortages. 
The world escaped a nuclear conflagration during the Cuban Missile Crisis, but the preceding scenario was a real possibility. Washington attempted to prepare for nuclear war in a variety of ways, but fallout shelters were the largest and most visible civil defense project carried out during the Cold War. Click on the following links for a history of the fallout shelter in D.C.
 Scenario taken from: Krugler, David F. This is Only a Test: How Washington, D.C. Prepared for Nuclear War. New York: Palgrave Macmillan, 2006, 179.