The Royal Castle is seen a veil of heavy winter smog in Budapest, Hungary on January 30, 2017. (Photo by Laszlo Balogh/Reuters)

A couple wears face masks as they share a moment during sunset on January 31, 2020 in Hong Kong, China. With over 9800 confirmed cases of Novel coronavirus (2019-nCoV) around the world, the virus has so far claimed over 200 lives. (Photo by Anthony Kwan/Getty Images)

A Palestinian boy holds an umbrella as he runs near houses that witnesses said were destroyed or damaged by Israeli shelling during the most recent conflict between Israel and Hamas, on a rainy day in the east of Gaza City November 16, 2014. (Photo by Suhaib Salem/Reuters)

A clown checks her phone as she waits outside the Basilica of Our Lady of Guadalupe, in Mexico City, Monday, December 14, 2015. Hundreds of clowns belonging to various clown associations made their annual pilgrimage to the Basilica on Monday to pay their respects to the Virgin of Guadalupe, Mexico's patron saint. (Photo by Rebecca Blackwell/AP Photo)

A passenger takes off his pants as others not wearing pants dance while waiting for a subway train during the “No Pants Subway Ride” in Mexico City, Mexico, February 21, 2016. The event is an annual flash mob and occurs in different cities around the world, according to its organisers. (Photo by Carlos Jasso/Reuters)

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)

People take photos with the skyline of the central business district in Singapore on September 10, 2015. (Photo by Edgar Su/Reuters)

Beautiful red sunset sky over Edinburgh, Scotland. Edinburgh is the capital city of Scotland and a popular tourist destination. It is also a major European financial (fund management) centre. Prominent buildings from left to right are: Edinburgh Castle, The Balmoral Hotel Clock Tower and The Scott Monument. (Photo by John Lawson/Getty Images)