Soldiers stand guard in Maua square where a cotton candy vendor passes by in Rio de Janeiro, Brazil, Saturday, July 9, 2016, as security is deployed to get to know the areas they'll be patrolling during the Olympics. Roughly twice the security contingent at the London Olympics will be deployed during the August games in Rio, which are expected to draw thousands of foreigners to a city where armed muggings, stray bullets and turf wars between heavily armed drug gangs are routine. (Photo by Leo Correa/AP Photo)

In this January 23, 2021, file photo, a police officer detains a young woman during a protest against the jailing of opposition leader Alexei Navalny in Pushkin square in Moscow, Russia. Allies of Navalny are calling for new protests next weekend to demand his release, following a wave of demonstrations across the country that brought out tens of thousands in a defiant challenge to President Vladimir Putin. (Photo by Alexander Zemlianichenko/AP Photo/File)

Girls in red neckerchiefs dance on Red Square, with the GUM, the State Department Store and the Historical Museum in the background, during a ceremony to celebrate joining the Pioneers organization and 100th anniversary of the All-Union Pioneer Organization, in Moscow, Russia, Sunday, May 22, 2022. Pro-Communist Russians are trying to preserve the Young Pioneers, which used to be the Communist league for pre-teens in the Soviet Union. (Photo by AP Photo/Stringer)

Hostesses wait to direct delegates to their buses and hotels after the opening session of the CPPCC, or Chinese Peoples Political Consultative Conference, in Tiananmen Square outside the Great Hall of the People on March 4, 2024 in Beijing, China.China's annual political gathering known as the Two Sessions will convene leaders and lawmakers to set the government's agenda for domestic economic and social development for the year. (Photo by Kevin Frayer/Getty Images)

Yoga practitioners participate in yoga classes inside Times Square on the day of the summer solstice in New York City on June 20, 2024. The annual all-day outdoor yoga event, which is in its 22nd year, features classes from sun up to sun down in one of the busiest intersections of the world. (Photo by Andrew Schwartz/Splash News and Pictures)

“Igor Sikorsky (May 25, 1889 – October 26, 1972), born Igor Ivanovich Sikorsky was a Russian American pioneer of aviation in both helicopters and fixed-wing aircraft. He designed and flew the world's first multi-engine fixed-wing aircraft, the Russky Vityaz in 1913, and the first airliner, Ilya Muromets, in 1914. After immigrating to the United States in 1919, Sikorsky founded the Sikorsky Aircraft Corporation in 1923, and developed the first of Pan American Airways' ocean-conquering flying boats in the 1930s. In 1939 Sikorsky designed and flew the Vought-Sikorsky VS-300, the first viable American helicopter, which pioneered the rotor configuration used by most helicopters today. Sikorsky would modify the design into the Sikorsky R-4, which became the world's first mass-produced helicopter in 1942”. – Wikipedia

Photo: Westland Sikorsky H-5's, used by British European Airways Helicopters, which fly between London and Birmingham. The Sikorsky H-5, (aka R-5, S-51, HO3S-1, or Horse) (R-5 until 1948; company designation VS-327) is a helicopter built by Sikorsky Aircraft Corporation, formerly used by the United States Air Force, and its predecessor, the United States Army Air Forces, as well as the United States Navy and United States Coast Guard (with the designations HO2S and HO3S). (Photo by Harrison /Topical Press Agency/Getty Images). 22nd May 1951

A man gestures to a robot at a restaurant in Hefei, Anhui province, December 26, 2014. The restaurant, with a space of 1300 square metres and a total of 30 robots to cook meals, deliver dishes and welcome costumers, was reported to be the biggest robot restaurant in China. (Photo by Reuters/Stringer)

Bryan Berg was introduced to card-stacking by his grandfather at the age of 8. He is a self-taught artist in all of the techniques he uses today. Berg's freestanding card structures are based on a grid-like arrangement, which Berg tested in a structural engineering lab to support 660 lbs per square foot―using no tape, no glue, no folding, and no tricks.