Runners hoist another runner into the air after completing The Color Run All-Star 5K as part of the All-Star Baseball game festivities, Saturday, July 11, 2015, at Sawyer Point Park, in Cincinnati. After more than two years of planning and sprucing up, city organizers say everything's in place for a smooth, safe and fun five days of events that began Friday morning with the opening of Major League Baseball's fan festival. There will be concerts, exhibits, celebrity softball, the Home Run Derby and other activities capped by Tuesday night's game. (Photo by John Minchillo/AP Photo)

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)

A motor taxi driver gets his hands washed at an Ebola screening station on the road between Butembo and Goma on July 16, 2019 in Goma. The first patient to be diagnosed with Ebola in the eastern DR Congo city of Goma has died, the governor of North Kivu province said on July 16, 2019. The case – the first in a major urban hub in the region's nearly year-old epidemic of the disease – has sparked deep concern in neighbouring Rwanda and at the UN. (Photo by John Wessels/AFP Photo)

Seven-year-old Mimi Meade winces from the sting as Dr. Richard Mulvaney inoculates her April 26, 1954 in McClean, Va., with the new Salk polio vaccine. Mrs. John Lucas, a registered nurse, holds Mimi's arm steady as she gets one of the first injections of the countrywide test. (Photo by Harvey Georges/AP Photo)

Senegalese wrestlers cover themselves in sand as they prepare to start their training program in Petit Mbao on March 29, 2021. As Covid-19 restrictions have been lifted, wrestlers now start prepare themselves for the start of wrestling tournaments. Senegalese wrestling, which has its roots in the ceremonies celebrating the end of harvests in Serer and Diola ethnic groups and remains surrounded by a thick cloud of mystical practice, is still extremely popular in this West African country. (Photo by John Wessels/AFP Photo)

Soldiers from the Nigerian Armed Forces take position and secure the streets in Lagos Island, Lagos, on February 27, 2023, after hoodlums had harassed market owners. Nigeria slowly counted more results on Monday after a tight election for the presidency of Africa's most populous nation as delays and accusations of manipulation fuelled tensions Nearly 90 million were eligible to vote on Saturday for a successor to President Muhammadu Buhari, with many hoping for a new leader to tackle insecurity, economic malaise and widening poverty. (Photo by John Wessels/AFP Photo)

Riot police face off with demonstrators at the “Occupy Denver” camp on October 29, 2011 in Denver, Colorado. Following a march by protesters, police moved in on their encampment to tear down recently erected tents. They arrested numerous protesters, pepper-sprayed others and others reportedly fired rubber bullets at the crowd during the confrontation. (Photo by John Moore/Getty Images)