U.S. Marines, left, and South Korean Marines, wearing blue headbands on their helmets, take positions after landing on the beach during the joint military combined amphibious exercise, called Ssangyong, part of the Key Resolve and Foal Eagle military exercises, in Pohang, South Korea, Saturday, March 12, 2016. North Korea said Saturday its military is ready to pre-emptively attack and “liberate” the South in its latest outburst against the annual joint military drills by the United States and South Korea. (Photo by Kim Jun-bum/Yonhap via AP Photo)

“The September 11 attacks (called September 11, September 11th or 9/11), were a series of four coordinated suicide attacks against targets in New York City and the Washington, D.C. area on September 11, 2001. On that morning, 19 terrorists from the Islamist militant group al-Qaeda hijacked four passenger jets. The hijackers intentionally crashed two planes into the Twin Towers of the World Trade Center in New York City; both towers collapsed within two hours. Hijackers crashed a third plane into the Pentagon in Arlington, Virginia. When passengers attempted to take control of the fourth plane, United Airlines Flight 93, it crashed into a field near Shanksville, Pennsylvania, preventing it from reaching its intended target in Washington, D.C. Nearly 3,000 died in the attacks”. – Wikipedia

Photo: A firefighter breaks down after the World Trade Center buildings collapsed September 11, 2001 after two hijacked airplanes slammed into the twin towers in a terrorist attack. (Photo by Mario Tama/Getty Images)

A man runs after he tried to put himself on fire during a protest at a makeshift camp at the Greek-Macedonian border near the village of Idomeni on March 22, 2016. Greece will not be able to start sending refugees back to Turkey from March 20, 2016, the government said, as the country struggles to implement a key deal aimed at easing Europe's migrant crisis. The numbers are daunting: officials said as of Saturday there were 47,500 migrants in Greece, including 8,200 on the islands and 10,500 massed at the Idomeni camp on the Macedonian border. (Photo by Andrej Isakovic/AFP Photo)

American model Bella Hadid poses as she arrives for the screening of the film “Tre Piani” (Three Floors) at the 74th edition of the Cannes Film Festival in Cannes, southern France, on July 11, 2021. (Photo by Reinhard Krause/Reuters)

In this photo taken Saturday, January 24, 2015, a child makes a face while having her photo taken with the snow covered slopes of the Nanshan ski resort behind her in Beijing. As Beijing makes a final push in its bid for the 2022 Winter Olympics, Chinese President Xi Jinping says winning the bid will encourage over 300 million Chinese to take up winter sports by 2022, according to state-run Xinhua News agency. (Photo by Ng Han Guan/AP Photo)

A gaucho is unseat by a wild horse during the annual celebration of Criolla Week in Montevideo, March 30, 2015. Throughout Easter Week, “gauchos”, the Latin American equivalent of the North American cowboy, from all over Uruguay and neighboring Argentina and Brazil will visit Montevideo to participate in the Criolla Week to win the best rider award. The competition is held from March 29 to April 5 this year. (Photo by Andres Stapff/Reuters)

These are the ambitious plans which suggest skyscrapers of the future may house an entire city. The Endless City project is an award-winning proposal by sure Architecture, who propose turning skyscrapers into complete ecosystems. London is the proposed city for the mixed-use tower – which would feature huge ramps linking different sections of the structure. The company, whose design won the SkyScrapers and SuperSkyScrapers Competition, insist the structure would be a great space-saver in dense cities which have previously spread outwards rather than upwards. (Photo by Caters News)

A man tries to photograph the interior of the driver's cab belonging to Eurostar's new Siemens e320 train at St Pancras station in central London, November 13, 2014. Eurostar, the company that runs passenger trains through the Channel tunnel between London and Paris, said it would buy seven additional e320 trains from Siemens for about 300 million pounds ($473 million). The company placed an order for 10 new trains in 2010, the first of which is due to enter commercial service next year, enabling the company to add new routes. (Photo by Andrew Winning/Reuters)