Train attendants take part in a parade training as they visit the national flag guard during a patriotic education event ahead of the 90th anniversary of the founding of the Chinese People's Liberation Army (PLA) in Beijing, China July 25, 2017. (Photo by Reuters/China Stringer Network)

Members of the San Francisco Gay Freedom Day Marching Band and Twirling Corps do their thing down San Francisco's Market Street, June 27, 1982. Police estimate the crowd to be 300,000 for the Lesbian/Gay Freedom Day parade and rally. (Photo by Carl Viti/AP Photo)

Roof-topping enthusiast Daniel Lau takes a selfie with high-rise buildings down below as he stands on the top of a skyscraper in Hong Kong, China on August 15, 2017. A craze that began in Russia has now taken hold in Hong Kong, one of the world's most vertical cities. Mr Lau said he had been inspired by Russian climbers and that he was unafraid of the vertiginous heights he scales. (Photo by ImagineChina/Rex Features/Shutterstock)

Cave Diver, Anhumas Abyss, Bonito, Brazil: The Anhumas Abyss is an underground cavern with a crystal-clear lake below, more than 260 feet (79 m) deep. A visitor must enter through a narrow opening at the top of the chamber and rappel into the cave. Snorkeling and scuba diving in the lake reveal amazing scenery. Distinctive, conical limestone stalagmites and stalactites occupy the lake and the surrounding area, some reaching 65 feet (20 m) high. (Photo by Marcio Cabral/Nature’s Best Photography Awards 2017)

Palestinian man Mohammed al-Hoor, 23, demonstrates his street workout skills in Nuseirat refugee camp, in the central Gaza Strip on May 2, 2017. (Photo by Mohammed Salem/Reuters)

A woman fills her basket with marigold flowers, used to make garlands and offer prayers, as she plucks them before selling to the market for the Tihar festival, also called Diwali, in Kathmandu, Nepal on October 25, 2019. (Photo by Navesh Chitrakar/Reuters)

A guest proposes to his companion as they arrive for the screening of “Mektoub, My Love: Intermezzo” during the 72nd annual Cannes Film Festival, in Cannes, France, 23 May 2019. The movie is presented in the Official Competition of the festival which runs from 14 to 25 May. (Photo by Julien Warnand/EPA/EFE)

A cat dressed in a traditional outfit takes part during the Orthodox Christmas celebration in Kiev, Ukraine on January 7, 2020. Orthodox Christians celebrate Christmas Day on December 25 of the older Julian calendar, which currently corresponds to January 7 in the Gregorian calendar. (Photo by Pavlo Gonchar/SOPA Images/LightRocket via Getty Images)