Firefighters watch as an air tanker drops retardant while battling the Ferguson fire in the Stanislaus National Forest, near Yosemite National Park, California on July 21, 2018. A fire that claimed the life of one firefighter and injured two others near California's Yosemite national park has almost doubled in size in three days, authorities said Friday. (Photo by Noah Berger/AFP Photo)

Korean People's Army (KPA) soldiers march during a mass rally on Kim Il Sung square in Pyongyang on September 9, 2018. Thousands of North Korean troops followed by artillery and tanks paraded through Pyongyang on September 9 as the nuclear-armed country celebrated its 70th birthday, but it refrained from displaying the intercontinental ballistic missiles that have seen it hit with sanctions. (Photo by Ed Jones/AFP Photo)

The Breitling DC-3, HB-IRJ, plane fly escorted by Italian Air Force's aerobatic demonstration team, the Frecce Tricolori, during the last stage of its world tour two days ahead of the International Sion Air Show, in Sion, Switzerland, 13 September 2017. From March to September 2017, the Breitling DC-3 from 1940 has done a grand world tour in several stages, over 28 countries and flies 50000km, an amazing accomplishment for this legendary plane that will be celebrating its 77th birthday. (Photo by Christian Merz/EPA/EFE)

A man fires a weapon as he dances during a traditional excursion near the western Saudi city of Taif, August 8, 2015. Saudis usually party in such excursions as they celebrate weddings or graduations. (Photo by Mohamed Al Hwaity/Reuters)

A woman carrying cabbage leaves on her head buys tomato at a market in Ahmedabad, India, November 9, 2015. India's villages face a sharp spike in food prices in 2016, as a second year of drought drives up the cost of ingredients such as sugar and milk, and poor transport infrastructure stops falling global prices from reaching rural areas. (Photo by Amit Dave/Reuters)

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.

Dancers Amy Hadley and Bethany Kingsley-Garner from the Scottish Ballet wait backstage during the dress rehearsal of the current production of “Sleeping Beauty” at the Theatre Royal on December 16, 2011 in Glasgow, Scotland. (Photo by Jeff J Mitchell/Getty Images)