South Korea's Black Eagles aerobatics team perform a maneuver during a preview of the Singapore Airshow at Changi exhibition center in Singapore February 14, 2016. The Airshow will take place from February 16-21. (Photo by Edgar Su/Reuters)

Soldiers from Japan's Ground Self Defense Force come ashore in amphibious assault vehicle as they train alongside U.S. Marines during the bilateral annual Iron Fist military training exercise in Camp Pendleton, California February 26, 2016. (Photo by Mike Blake/Reuters)

Skiers and snowboarders in swimwear during the Grelka Fest-2019 Festival at the Sheregesh ski resort, Kemerovo Region, Russia on April 13, 2019. (Photo by Kirill Kukhmar/TASS)

“Dover Castle is a medieval castle in the town of the same name in the English county of Kent. It was founded in the 12th century and has been described as the “Key to England” due to its defensive significance throughout history. It is the largest castle in England.

The outbreak of the Second World War in 1939 saw the tunnels converted first into an air-raid shelter and then later into a military command centre and underground hospital. In May 1940, Admiral Sir Bertram Ramsey directed the evacuation of French and British soldiers from Dunkirk, code-named Operation Dynamo, from his headquarters in the cliff tunnels”. – Wikipedia

Photo: The Repeater Station in the subterranean tunnels underneath Dover Castle, which has been restored by English Heritage for a public exhibition on June 3, 2011 in Dover, England. The evacuation of allied soldiers from Dunkirk was masterminded and co-ordinated from the secret command and control centre in the tunnels deep below the castle. (Photo by Matthew Lloyd/Getty Images)

Visitors look up at mock-ups of dinosaur skeletons inside the Museum of Natural History in Pyongyang on September 28, 2016. (Photo by Ed Jones/AFP Photo)

Enthusiasts gathered at Cad East in Snowdonia National Park, England to take pictures of F-15 Eagle fighters as they completed the Mach Loop, November 2017. (Photo by Caters News Agency)

People wearing face masks to protect against the spread of the coronavirus walk on a crossing in Tokyo Tuesday, August 17, 2021. Japan’s coronavirus state of emergency will continue through Sept. 12 rather than finishing at the end of this month as initially planned, the government decided Monday. (Photo by Koji Sasahara/AP Photo)

A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)