Young Buddhist novice monks play at a Tibetan nomadic summer grazing area on July 24, 2015 on the Tibetan Plateau in Yushu County, Qinghai, China. Tibetan nomads face many challenges to their traditional way of life including political pressures, forced resettlement by China's government, climate change and rapid modernization. The Tibetan Plateau, often called “The Roof of the World”, is the world's highest and largest plateau. (Photo by Kevin Frayer/Getty Images)

Dajana Djuric, 25, who has worked as a chimney sweep since the age of six, cleans a chimney in Brcko, Bosnia and Herzegovina. Dajana Djuric, believed to be the only female chimney sweep in Bosnia and Herzegovina, has to contend with perilous roofs in the depth of winter. (Photo by Dado Ruvic/Reuters)

Cooperation is key to success. This motto was used by the Government of Denmark when they decided to create a project that bore the name of UN City. This compound was designed to house all nine Copenhagen based UN agencies under a single roof. This embodies the core idea of the United Nations, since this project allows for better efficiency and practicality thanks to joint effort. The first plans for the UN City were hatched in 2002. After 11 years, in 2013 the first stage of the project was finally finished. Presently, Campus 1 of UN City accommodates 1,300 staff member, while Campus 2 is going to become the largest humanitarian warehouse in the whole world.

A guest poses for photographs at the infinity pool of the newly-inaugurated Dolce Hanoi Golden Lake hotel, the world's first gold-plated hotel, in Hanoi on July 2, 2020. It even has a gold-plated infinity pool on the roof. The 400-room, 25-storey property will operate under the American Wyndham Hotels brand. Prices start at $300 a night for rooms, or there are apartments to rent costing from $6400 per square metre. (Photo by Manan Vatsyayana/AFP Photo)

Carine Louis-Jean, 22, poses for a photograph in her destroyed house after Hurricane Matthew hit Jeremie, Haiti, October 17, 2016. “The roof of my house is completely gone and some of walls were destroyed. I have lost everything I had, but I thank God that I have a friend who is letting me stay at her house. I could say I'm lucky, because none of my family died during the hurricane, but I do not think I'm lucky”, said Louis-Jean. (Photo by Carlos Garcia Rawlins/Reuters)

Family members mourn the passing of Manuela Chavez, who died from symptoms related to the new coronavirus at the age of 88, as a government team prepares to remove her body from inside her home, in the Shipibo Indigenous community of Pucallpa, in Peru's Ucayali region, Monday, August 31, 2020. While the lucky are cured with ancestral ailments, the less fortunate often die at home. A government team travels from one spartan, thatch-roofed home to the next, removing the dead from their homes where they took their last breaths. (Photo by Rodrigo Abd/AP Photo)

A cenote is a natural phenomenon, a sinkhole in the Earth’s surface. The Yucatan Peninsula in Mexico has an estimated 7,000 cenotes because it is primarily made up of porous limestone. For millions of years, rainfall slowly ate away at the limestone and a huge system of underground caves and caverns was formed. Many filled with water from rain or from the underground water table. When the roof of a water filled cave collapses, a cenote is born. The water found in a cenote may be fresh water, salt water, or both. Structurally it may be completely open, like a lake, almost completely closed with just a small opening at the top, or somewhere in between.

To an outsider, their passion is at times illegal and often on the verge of life and death. But climbing rooftops of high-rise buildings and exploring abandoned facilities is in the blood of these young Muscovites. The small group calls itself “Rudex”, which stands for “roof and decay exploration”, and is akin a Western youth craze known as urbex or “urban exploration” of man-made structures. Here: Urban explorer Vad Him of Rudex team jumps whilst on a rooftop in Moscow, Russia, August 14, 2017. (Photo by Maxim Shemetov/Reuters)