Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

An Airbus A380 aircraft prepares to land at Mumbai airport in this May 8, 2007 file photo. Sentiment at some of Asia's biggest firms deteriorated again in the fourth quarter, falling to a four-year low under the weight of concerns about slowing growth in China, the region's biggest economy, a Thomson Reuters/INSEAD survey showed. (Photo by Arko Datta/Reuters)

Visitors look at an artwork “Hierarchy of Prosperity” created by Indonesian artist Eko Nugroho during the VIP preview of the art fair “Art Basel” in Hong Kong, Tuesday, March 22, 2016. A set of gold-plated metal cubes, tapestries embroidered by unknown North Korean artisans and bales of cardboard waste are among the highlights of the Art Basel Hong Kong fair opening this week. (Photo by Kin Cheung/AP Photo)

Bangladeshi pedestrian cross a broken baily brideg on July 7, 2019 in Sylhet. Heavy vehicle movement was restricted in this bridge but when a cement bag loaded truck got into the bridge, Suddenly, it collapse. (Photo by AFP Photo/Stringer)

Models, painted by bodypainting artist Alex Hansen from Brasil and Benoit Botella from Guadaloupe, pose for a picture at the 21st World Bodypainting Festival 2018 on July 14, 2018 in Klagenfurt, Austria. (Photo by Didier Messens/Getty Images)

Makeup artist He Yuhong, also known as “Yuya”, checks herself in the mirror during a photo shoot following her transformation into the “Girl with a Pearl Earring”, the 17th century oil painting by Dutch painter Johannes Vermeer, at her house in Chongqing, China on August 14, 2018. (Photo by Thomas Suen/Reuters)

Fiona McGarva holds one of the sculptures from the art installation Gratitude at The Forth Bridge at North Queensferry on September 15, 2021, ahead of going on display just outside of Edinburgh at Newhailes House and Gardens from Friday 17th September. The public art installation pays tribute to NHS staff and all key workers for their ongoing courage and dedication during the Covid-19 pandemic. (Photo by Andrew Milligan/PA Images via Getty Images)

A Palestinian clown on stilts walks on a street amid the outbreak of the coronavirus disease (COVID-19), in Gaza City on November 20, 2020. (Photo by Suhaib Salem/Reuters)