Nuns from the United States dance as they wait for the Holy Mass with Pope Francis (not seen) at the Campus Misericordiae in Brzegi, Poland, 31 July 2016. Today Pope Francis will celebrate the holy mass ending the World Youth Day 2016 in Poland. (Photo by Marcin Obara/EPA)

Vardzia is a cave monastery site in southern Georgia, excavated from the slopes of the Erusheti Mountain on the left bank of the Mtkvari River, thirty kilometres from Aspindza. The main period of construction was the second half of the twelfth century. The caves stretch along the cliff for some five hundred metres and in up to nineteen tiers. The Church of the Dormition, dating to the 1180s during the golden age of Tamar and Rustaveli, has an important series of wall paintings. The site was largely abandoned after the Ottoman takeover in the sixteenth century. Now part of a state heritage reserve, the extended area of Vardzia-Khertvisi has been submitted for future inscription on the UNESCO World Heritage List

Tommy Lindsey holds an enormous maple leaf that he found in Mount Vernon, Wash., October 28, 2013. Lindsey was walking with his family when he picked up the leaf that is more than two feet from stem to tip and more than 21 inches wide. (Photo by Frank Varga/The Skagit Valley Herald)

In this photo taken on Saturday, November 16, 2013, Mt. Etna, Europe's most active volcano, spews lava during an eruption as seen from Acireale, near the Sicilian town of Catania, Italy. (Photo by Carmelo Imbesi/AP Photo)

A man from Dinka tribe holds his AK-47 rifle in front of cows in a Dinka cattle herders camp near Rumbek, capital of the Lakes State in central South Sudan December 14, 2013. (Photo by Goran Tomasevic/Reuters)

Chile's Javier Campillay drives past the burning car of Kazakhstan's Bauyrzhan Issabayev and Gabdulla Ashimov during the Dakar Rally 2014 Stage 2 from San Luis to San Rafael, on January 6, 2014. (Photo by Jean-Paul Pelissier/AFP Photo)

NYC morning fog. Wednsday, January 15, 2014, morning dense fog creates spectacular views over the East river of lower Manhattan, Brooklyn and Manhattan bridges as New Yorkers and tourist admire the scenery. View from Brooklyn Bridge Park in DUMBO Brooklyn. (Photo by Paul Martinka/New York Post)

A competitor reacts as she emerges from the water during the Tough Guy event in Perton, central England, January 26, 2014. The annual Tough Guy race – “the toughest race in the world” – at Perton in Staffordshire. Tough Guy claims to be the world’s most demanding one-day survival ordeal. First staged in 1987, the Tough Guy Challenge has been widely described as one of the hardest races of it’s type with up to one-third of the starters failing to finish in a typical year. (Photo by Darren Staples/Reuters)