A window cleaner passes a lighter to his colleague while rappelling from a new building in Tianjin March 23, 2007. (Photo by Reuters/Stringer)

Sgt. William Olas Bee, a U.S. Marine from the 24th Marine Expeditionary Unit, has a close call after Taliban fighters opened fire near Garmsir in Helmand Province of Afghanistan, May 18, 2008. (Photo by Goran Tomasevic/Reuters)

Travis Gerrits of Canada competes during qualifying for the Mens Aerials at the FIS Freestyle Ski World Cup Aerial Competition at Deer Valley on January 10, 2014 in Park City, Utah. (Photo by Mike Ehrmann/Getty Images)

A rabbit fails to clear an obstacle during a bunny hop competition at the Old Town Square in Prague, Czech Republic, Monday, April 14, 2014. (Photo by Petr David Josek/AP Photo)

Waldo, a 6-year-old Tibetan Terrier belonging to Susan and Mike Leverette of Sebastian, competes in the third heat of the medium dogs division at the Hang 20 Surf Dog Classic at Carlin Park in Jupiter Saturday, August 29, 2015. “The waves are a little bigger than we are used to”, said Susan. (Photo by Bruce R. Bennett/The Palm Beach Post)

Aerial photo taken on March 4, 2017 shows cole flower fields in Luoping County, southwest China's Yunnan Province. (Photo by Xinhua/Barcroft Images)

A period of relative stability has put the Iranian capital No1 on the list of world cities that have achieved biggest improvements in liveability over the past five years, as calculated by the Economist Intelligence Unit. The “most improved” top 10 contains some unexpected names. So, eg, the fourth place: Abidjan, Ivory Coast. Latest ranking: 128; Ranking five years ago: 131; Five-year index movement: 3.8%. Here: A supporter of Ivory Coast president Alassane Ouattara campaigns in a market in the city’s Koumassi quarter. (Photo by Sia Kambou/AFP 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