In this December 18, 2013 photo released by Six Flags Discovery Kingdom, 32 men dressed as Santa Claus ride the 150-foot tall SkyScreamer tower swing ride at Six Flags Discovery Kingdom in Vallejo, Calif. (Photo by Jason Quintos/AP Photo/Six Flags Discovery Kingdom)

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.

Every year, in the Rostov region of Russia, a group of 40 young and not so young rural workers compete in the Bison Track Show, or more affectionately known as: Russian Flying Tractor Racing. In front of crowds numbering up to 30,000 people, a series of smoke spilling, monstrous farming machines tear round an 8km mud track, plowing through lakes and dirt mounds, their turbos screaming and tyres scrabbling to find grip.

Amazing gravity-defying photo manipulations by Ravshaniya, a photographer from Uzbekistan, teeters on the edge of levitation. Photo: Untitled. (Photo by Ravshaniya)

Palestinians and Israelis enjoy the Mediterranean sea during the first day of the Eid al-Fitr holiday in Tel Aviv, Israel, Thursday, August 8, 2013. The three-day Eid al-Fitr holiday marks the end of the holy fasting month of Ramadan. One of the most important holidays in the Muslim world, Eid al-Fitr, is marked with prayers, family reunions and other festivities. (Photo by Oded Balilty/AP Photo)

US marines watch the mushroom cloud from an atomic explosion rise above the Yucca flats, Nevada during a US nuclear weapons test. (Photo by Keystone/Getty Images). USA, 1945

A giant sculpture of a seven-month-old baby by artist Marc Quinn entitled “Planet” contrasts against the stately grandeur of Chatsworth House and the Derbyshire countryside on 4 September, 2008, Chatsworth, England. The bronze sculpture painted white is part of the Beyond Limits exhibition of modern and contemporary sculpture displayed in the gardens of Chatsworth by Sotherby's. More than 20 works will be on display from 9 September to 2 November 2008. In past years acclaimed artists Damien Hirst, Antony Gormley, Salvador Dali and Henry Moore have had work exhibited. (Photo by Christopher Furlong/Getty Images)

Paint splattered police officers look on during clashes outside Top Shop on Oxford Street, during marches in protest at government cuts on March 26, 2011 in London, England. Thousands are taking part in the Trades Union Congress (TUC) organised march to Hyde Park where a rally will take place. Police say they are deploying 4500 officers. (Photo by Dan Kitwood/Getty Images)