A glass skywalk in Wanyuan, Sichuan province, built along the side of a cliff, is the highest such skywalk anywhere in China on January 31, 2017. Some visitors have been proven to be terrified by the experience had to brace against the wall in fear. (Photo by Chinanew.com/AsiaWire)

A Nepalese man sits outside a Hindu temple as a goat rests on a parked scooter in Khokana, Lalitpur District, Nepal, Monday, September 26, 2016. Writing on the wall offers prayers to Hindu god Shiva. (Photo by Niranjan Shrestha/AP Photo)

Tourists pose for a selfie in an old American car in front of a wall bearing a graffiti of the Committees for the Defense of the Revolution (CDR) in Havana, on September 27, 2023. September 28 marks the 63th anniversary of the Committees for the Defense of the Revolution (CDR), the so-called “eyes and ears of the Revolution” created by the late Cuban leader Fidel Castro. (Photo by Yamil Lage/AFP Photo)

A migrant labourer gets a shave besides a closed shop in a market area in the old quarters of the walled city, Delhi during an ongoing state-wide weekend curfew imposed by the directive of the Delhi government to curb the spread of the Covid-19 coronavirus in New Delhi on January 9, 2022. (Photo by Money Sharma/AFP Photo)

A man works on a small replica of the Iron Man armor next to a homemade replica of the “Hulkbuster” Iron Man armour from the movie “Avengers: Age of Ultron”, at an underground parking lot in Zhengzhou, Henan province, China, May 12, 2015. The 3.4-metre-tall replica is made of over 100 fiber-reinforced plastic components. It took Xing and his friends two months to put them together after watching the trailer of the movie in March, local media reported. (Photo by Reuters/Stringer)

Soap Bubble Structures by Kym Cox. Bubbles optimise space and minimise their surface area for a given volume of air. This phenomenon makes them a useful tool in many areas of research, in particular, materials science and “packing” – how things fit together. Bubble walls drain under gravity, thin at the top, thick at the bottom, which interferes with travelling lightwaves to create bands of colour. Black spots show the wall is too thin for interference colours, indicating the bubble is about to burst. (Photo by Kym Cox/2019 Science Photographer of the Year/RPS)

A woman walks past graffiti on a wall in the Williamsburg neighborhood of the borough of Brooklyn, in New York, September 16, 2014. The picture was taken through car window with raindrops. (Photo by Shannon Stapleton/Reuters)

A hostess sits at a restaurant with paintings depicting Thailand's King Bhumibol Adulyadej hanging on a wall in Bangkok, Thailand, June 6, 2016. (Photo by Athit Perawongmetha/Reuters)