The National September 11 Memorial & Museum (branded as 9/11 Memorial and 9/11 Memorial Museum) is the principal memorial and museum commemorating the September 11 attacks of 2001, which killed nearly 3,000 people, and the World Trade Center bombing of 1993, which killed six. The memorial is located at the World Trade Center site, on the former location of the Twin Towers, which were destroyed during the attacks. The World Trade Center Memorial Foundation was renamed the National September 11 Memorial & Museum at the World Trade Center in 2007.

A wildlife caregiver holds an orphaned wombat at the Native Wildlife Rescue center on January 29, 2020 in Robertson, Australia. The center has taken in many burned kangaroos and wallabies injured in recent bushfires. Wombat orphans are often rescued from the pouch of their mothers struck by vehicles. (Photo by John Moore/Getty Images)

Taylor Swift performs “All Too Well” at the 56th annual Grammy Awards at Staples Center. (Photo by Matt Sayles/Invision)

A baby Sumatran orangutan is bathed after arriving at a wildlife center at Ratchaburi province in Thailand September 13, 2017. (Photo by Kerek Wongsa/Reuters)

A blurred panaroma of Roemerberg historic center is reflected in a soap bubble in Frankfurt am Main, Germany, 09 July 2015. (Photo by Frank Rumpenhorst/EPA)

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.

A graffiti, portraying a woman, is seen in Medellin, Colombia on November 19, 2017. Mural graffitis from different artists, street art can be seen in almost every city on Earth, but street arts raw power and potential for change was felt by me most intensively in Medellins Comuna 13, previously one of Colombias most dangerous neighbourhoods, in fact Communa 13 was constant battleground between gangs, narcos, paramilitaries and the government, but today you would hardly recognise it. (Photo by Juancho Torres/Anadolu Agency/Getty Images)