Two canyon sites behind the fence at Los Alamos tell the Manhattan Project in miniature: a gun range that tested a bomb design and a quiet canyon where plutonium's flaw was found and a physicist died.
On 16 July 1945 a plutonium bomb nobody had ever fired was set off on a New Mexico tower after a night of storms. Trinity showed that implosion worked, and it shaped what came next at Potsdam, Hiroshima and Nagasaki.
Trinity Site is the New Mexico desert basin where the first atomic bomb was fired in 1945. An obelisk, a restored ranch house and a steel vessel still stand there, and the families downwind waited 80 years for recognition.
In September 1944 the world's first full-scale plutonium reactor went critical beside the Columbia River, then shut itself down a day later. B Reactor made plutonium for Trinity and Nagasaki, ran on into the Cold War, and now takes visitors on free tours.
Bakić's 37-metre monument to the 1941 uprising once glittered with Swedish stainless steel above the forests of central Croatia. Now it is stripped, graffitied and carrying phone antennas, and a Netflix crew has filmed in it.
In December 1943 the 150 people of Imber were told to leave their Wiltshire village for a few months so American troops could train there. They never came back, and the village still stands empty inside an army firing range.
Prora was meant to be a seaside holiday camp for 20,000 workers, a block of concrete 4.5 kilometres long on Rügen's Baltic coast. The war stopped it before a single holidaymaker arrived, and the shell went on to serve three armies before the luxury flats moved in.
Okunoshima is famous for the hundreds of rabbits that greet every ferry, but from 1929 to 1945 it was a secret island where the Imperial Japanese Army made thousands of tons of poison gas.
Along France's Atlantic coast, Germany built vast concrete bunkers for its U-boats during the Second World War. Bombers could not break them, and today they are museums, art galleries, naval stores and silent ruins.
On the cliffs near Cap Gris-Nez, four huge concrete casemates once held German naval guns that could hit the English coast. One of them is now a museum, and the rest still stand in the fields.
Built in the Second World War with a runway half as long again as normal, RAF Sculthorpe became one of the biggest US Air Force bases in Britain, home to nuclear-capable bombers until it closed in 1992.
Between 1943 and 1945 the Nazis dug into the gneiss of the Owl Mountains in Lower Silesia, using thousands of forced labourers to build seven underground sites. Nobody knows for sure what Project Riese, the Giant, was meant to be.
On 10 June 1944, four days after D-Day, a Waffen-SS company killed 642 people in a quiet village in west-central France and burned it. The ruins have never been rebuilt, and visitors still walk its streets beside the tram rails.
Hashima is a six-hectare rock off Nagasaki that held 5,259 people at its 1959 peak, packed into concrete apartment blocks around an undersea coal mine. Mitsubishi closed the mine in January 1974 and the island was emptied by April. It is now a World Heritage site, and its wartime forced-labour history is still disputed.
On 20 July 1944 Colonel Claus von Stauffenberg left a bomb in Hitler's briefing hut and flew to Berlin to launch a coup. Hitler survived, the coup collapsed within hours, and thousands were arrested in the reprisals that followed.
In March 1944, 76 Allied airmen crawled out of a tunnel beneath a German prison camp in Lower Silesia. Three reached home. Fifty were murdered on Hitler's orders. Today the camp site at Żagań is a museum and memorial.
On the night of 27 to 28 February 1942, 120 British paratroopers dropped into occupied Normandy, took apart a German Würzburg radar and carried the pieces to the beach. The raid cost a handful of men and handed British scientists the key to jamming it.
On 10 May 1940 Germany attacked the Netherlands, Belgium, Luxembourg and France. The Allies advanced to meet the main blow in Belgium, while the real thrust came through the Ardennes, crossed the Meuse at Sedan and reached the Channel in ten days.
In the early hours of 10 May 1940, German paratroopers landed gliders on the roof of Belgium's greatest fortress and disabled its guns with hollow-charge explosives. The fort surrendered the next day. Today it is a museum, with a stretch of its tunnels open to visitors.
On 6 June 1944 the Western Allies landed in Normandy from a fleet of nearly 7,000 vessels, after a year of planning, a major deception campaign and a one-day weather delay. By the end of the day all five beachheads were won, but at a heavy cost, and most of the day's objectives were still ahead.
On the morning of 6 June 1944, 225 U.S. Rangers climbed a 30-metre cliff in Normandy under fire to capture a German gun battery. The guns were not in their casemates. Today the cratered headland is a memorial site, and a restoration project is under way to protect it from erosion.
Inside the Kohnstein hill near Nordhausen, the SS and German industry built the V-2 rocket with concentration camp labour. About 60,000 people passed through the Mittelbau-Dora camps, and at least a third did not survive. Part of the tunnel system can be visited on a guided tour.
In August 1943, nearly 600 bombers flew to the Baltic coast under a full moon to destroy the secret rocket centre at Peenemünde. They killed scientists and many prisoners, lost 40 aircraft, and pushed Germany's rocket programme underground.
On a sandy peninsula of the Baltic, German engineers built the world's first long-range ballistic missile, using forced labour to do it. The RAF bombed the site in 1943, the Soviets took what was left in 1945, and today a museum sits in its old power station.
