“The Challenge!” Young boy relishes in a game of tug of war before school. Photo location: Lake Titicaca, Peru. (Photo and caption by Paul Heyman/National Geographic Photo Contest)

At this year’s Venice Bienniale in Italy, the Korean pavilion has a curious exhibit called “Commissions for Utopia”. It includes renderings from North Korea’s top architects and artists (all anonymous), many of whom studied at the Paekho Institute of Architecture, North Korea’s state-run architectural college, and none of whom have ever left the country. They were asked to create a vision of North Korea’s future sustainable architecture for its expanding tourism industry. Their final products are a glimpse into what it would be like to envision the future after being entirely cut off from the present for almost 70 years. (Photo by Nick Bonner/Kyle Vanhemert/Venice Architecture Biennale)

World's Greatest Swimming Pools: Four Seasons, Serengeti Pool, Tanzania. A show of elephants, buffalo and baboons awaits thanks to an active watering hole below the free-form infinity pool at this plush hideaway inside Serengeti National Park. Bonus: Because of infrared technology at the hole, guests can be notified on their bedroom TV when animals are approaching. When you've got word of wildlife on the horizon, catch them from your private terrace – or head back to the pool. (From $1,650). (Photo by Four Seasons)

South Korean rescue members wearing chemical protective suits walk past a monster character (R) during an anti-terror drill as part of a disaster management exercise at the COEX shopping and exhibition center in Seoul on May 20, 2016. South Korea is holding its 2016 Safe Korea anti-disaster exercise this week against terrorist threats and natural disasters. (Photo by Jung Yeon-Je/AFP Photo)

A combination photo shows various popular street foods under $6 from various hawker food stalls and eateries in Singapore, taken between July 28 to 31, 2016. Top row (L to R) bak chor mee, soya sauce chicken; Middle row (L to R) laksa, hokkien mee, nasi lemak, ice kachang; Bottom row (L to R) rojak, roti prata and satay. (Photo by Edgar Su/Reuters)

A woman presents an Afro-Colombian hairstyle during the 9th contest of Afro-hairdressers, in Cali, Valle del Cauca departament, Colombia, on May 12, 2013. The Afro hairstyles have their origins in the time of slavery, when women sat to comb their children hair after work. (Photo by Luis Robayo/AFP Photo)

A family poses for a picture in front of the carcasses of sacrificed buffalos a day after the sacrificial ceremony of the “Gadhimai Mela” festival held in Bariyapur November 29, 2014. Sword-wielding Hindu devotees in Nepal began slaughtering thousands of animals and birds in a ritual sacrifice on Friday, ignoring calls by animal rights activists to halt what they described as the world's largest such exercise. (Photo by Navesh Chitrakar/Reuters)

The competition, which is run by the Royal Observatory Greenwich in association with BBC Sky at Night Magazine, is now in its sixth year and has received over 2,500 entries. Photo: Centre of the Heart Nebula by Ivan Eder (Hungary). Situated 7500 light years away in the “W”-shaped constellation of Cassiopeia, the Heart Nebula is a vast region of glowing gas, energized by a cluster of young stars at its centre. The image depicts the central region, where dust clouds are being eroded and moulded into rugged shapes by the searing cosmic radiation. (Photo by Ivan Eder)