A team of ten acrobats form the shape of a racehorse crossing the winning post ridden by Stefanie Hofer to celebrate the upcoming Dubai Duty Free Shergar Cup at Ascot Racecourse on July 29, 2014 in Ascot, England. The Dubai Duty Free Shergar Cup is the only team-format raceday in the UK and takes place on 9th August. (Photo by Ian Gavan/Getty Images for Ascot Racecourse)

Participants hang from ropes as they learn how to use safety gears at an experience centre for construction safety training in Beijing, September 5, 2014. The centre which opened in June 2014 was established to educate workers about construction safety. According to the centre, about 1,000 construction workers undergo 3-hour classes which comprises of 33 modules every month. (Photo by Kim Kyung-Hoon/Reuters)

Dhruva Aliman does a back somersault as he dismounts from a slackline on the beach at Santa Monica, California on October 19, 2014. Slackline is a balance sport where a line of webbing is adjusted at different levels of tension between two anchor points and participants (called slackers) perform tricks and stunts including somersaults. (Photo by Mark Ralston/AFP Photo)

Russia's Maria Stavitskaia performs during the ladies short program at the Rostelecom Cup ISU Grand Prix of Figure Skating in Moscow November 14, 2014. (Photo by Grigory Dukor/Reuters)

Street fighting in Berlin between Government troops and Spartacists, during the Spartacist uprising which followed Germany's defeat in World War I. (Photo by Keystone/Getty Images). 1919

A British policewoman chasing after a group of naked street boys by the Serpentine in Hyde Park, London. (Photo by Reg Speller/Getty Images). 1926

“José Doroteo Arango Arámbula (5 June 1878 – 20 July 1923) – better known by his pseudonym Francisco Villa or its hypocorism Pancho Villa – was one of the most prominent Mexican Revolutionary generals”. – Wikipedia

Photo: Mexican rebel leader Francisco “Pancho” Villa with one of the motorcycles used in the Battle of Torrero. (Photo by Topical Press Agency/Getty Images). August 1914

Jockey student Mariangelys Almedina (Front) balances on a steel drum suspended in the air by a series of springs to simulate riding a horse as Instructor Willie Lozano looks on at the Vocational Equestrian Agustín Mercado Reverón School located in the Hipódromo Camarero on November 17, 2022 in Canovanas, Puerto Rico. The Vocational Equestrian Agustín Mercado Reverón School has produced some of the best jockeys in the world but also prepares students for a wide range of equestrian jobs on a tuition-free basis. (Photo by Al Bello/Getty Images)