A 20 metre high spiral staircase in a tower used as an emergency exit, is seen inside a Federal Reserve bank (Bundesbank) bunker, prior to the bunker's official opening to the public in Cochem, Germany, March 18, 2016. West Germany's Central Bank (Deutsche Bundesbank) stored some 20 billion German marks of emergency notes in two underground bunkers, one in Frankfurt the other in Cochem, between 1964-1988 during the cold war. (Photo by Kai Pfaffenbach/Reuters)

Floating on clear deep water and reflections near the cave entrance. Visitors can either bring their own kayaks or rent boats from the local community to paddle deep inside the cave and marvel at its wonders on March 2015 at Tham Khoun Ex, Laos. Tham Khoun Xe, commonly known as the Xe Bang Fai River Cave, in Laos, has over 15km of passages filled with awe-inspiring views and wide expanses of water. Photographer, John Spies, 59, captured scenes from the entrances of the huge underground river passages, intricate cave formations and views from a passage high above the water. The cave is formed by the Xe Bang Fai river, a major tributary of the Mekong and in the dry season can be traversed using inflatable kayaks. (Photo by John Spies/Barcroft Media/ABACAPress)

“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)

“The fennec fox is a small nocturnal fox found in the Sahara of North Africa. Its most distinctive feature is unusually large ears. The name “fennec” comes from the Arabic word for fox, and the species name zerda has a Greek origin that refers to its habitat. The fennec is the smallest species of canid in the world; coat, ears and kidney functions have adapted to a high-temperature, low-water, desert environment. In addition, its hearing is sensitive enough to hear prey moving underground”. – Wikipedia

Photo: A Baby Fennec is seen at Sunshine International Aquarium on June 24, 2009 in Tokyo, Japan. The small nocturnal fox babies were born on May 17 2009. (Photo by Junko Kimura/Getty Images)

Layers of breathtaking colour streak the rolling hills of this vast desert, making the landscape appear as though it has been tie-dyed. The natural phenomenon, nicknamed the “Painted Desert”, was formed when the area was once a river floodplain. Each colour corresponds to a different underground geological feature – rocks which have seemingly dyed the layers of earth above. Formed from volcanic activity, the hills at the John Day Fossil Beds National Monument in East Central Oregon, USA, are almost bursting with colour. Pictured: The colourful hills at the John Day Fossil Beds National Monument in East Central Oregon, USA. (Photo by Mark Brodkin/Solent News/SIPA Press)

Male is the capital and most populous city in the Republic of Maldives. The city is geographically located at the southern edge of North Malé Atoll (Kaafu Atoll). Administratively, it is a city-class constituency and is governed by the Malé City Council. Traditionally it was the King's Island, from where the ancient Maldive Royal dynasties ruled and where the palace was located. The city was then called “Mahal”. Formerly it was a walled city surrounded by fortifications and gates (doroshi).

A Manchester City fan attends the trophy ceremony after the end of the Soccer Club World Cup final match between Manchester City FC and Fluminense FC at King Abdullah Sports City Stadium in Jeddah, Saudi Arabia, Friday, December 22, 2023. Manchester City won 4-0. (Photo by Manu Fernandez/AP Photo)

In this handout image provided by the City of New York, a Nissan NV200 is seen as a New York City taxi cab in New York City. The Taxi and Limousine Commission along with New York City Mayor Michael Bloomberg announced the Nissan NV200 designed by Nissan North America, Inc., has been chosen as the winner of the Taxi of Tomorrow competition and will become the City's exclusive taxicab for a decade. (Photo by City of New York via Getty Images)