Željava Air Base, situated on the border between Croatia and Bosnia and Herzegovina under Plješevica Mountain, near the city of Bihać, Bosnia, was the largest underground airport and military air base in the former Yugoslavia, and one of the largest in Europe. (Photo by Thomas Windisch/Exclusivepix Media)

A Muslim woman prays at the Al Meroz hotel in Bangkok, Thailand, August 29, 2016. Predominately Buddhist Thailand has opened its first halal hotel as hopes to attract more Muslim visitors and boost one of the few bright spots in its economy. (Photo by Chaiwat Subprasom/Reuters)

Second Place Winner: “Thunderstorm at False Kiva”. I hiked out to these ruins at night hoping to photograph them with the Milky Way, but instead a thunderstorm rolled through, creating this dramatic image. – Max Seigal. National Geographic Traveler Director of Photography Dan Westergren, one of this year's judges, shares his thoughts on the second place winner: “This photo combines two different scenes into one: the small kiva in a cliff dwelling and the grand vista of Canyonlands National Park across the valley. I really like the two different color palettes – warm inside and purple outside. This two-for-one scene was caused by the lightning storm outside the dwelling, which lit up the landscape like it was a huge electronic flash. Looking at this picture I can imagine what a wonderful sight it must have been for the ancient people who lived here. It doesn't seem too amazing now in our modern world, but might have been mind-blowing for the prehistoric residents”. Location: Utah. (Photo and caption by Max Seigal/National Geographic Traveler Photo Contest)

Muslim girls are seen after prayers, in Lagos, Nigeria, Friday, July 31, 2020. Small groups of pilgrims performed one of the final rites of the Islamic hajj on Friday as Muslims worldwide marked the start of the Eid al-Adha holiday amid a global pandemic that has impacted nearly every aspect of this year's pilgrimage and celebrations. The last days of hajj coincide with the four-day Eid al-Adha, or “Feast of Sacrifice”, in which Muslims slaughter livestock and distribute the meat to the poor. (Photo by Sunday Alamba/AP Photo)

A man runs to help a woman as they attempt to shelter in a locked convenience store during heavy wind and rain as typhoon Maysak hits the Haeundae Beach area of Busan, South Korea, on September 3, 2020. Flights were grounded in South Korea and storm warnings issued on both sides of the Korean peninsula as a typhoon forecast to be one of the most powerful in years made its approach. (Photo by Ed Jones/AFP Photo)

A protestor is detained following the grand jury verdict on September 23, 2020 in Louisville, Kentucky. Protesters marched in the streets after a Kentucky grand jury indicts one of the three officers involved in the killing of Breonna Taylor, who was fatally shot by Louisville Metro Police officers during a no-knock warrant at her apartment on March 13, 2020 in Louisville, Kentucky. (Photo by Brandon Bell/Getty Images)

Alejandro Ccasa prays after waiting three days next to an empty oxygen tank for his uncle who has COVID-19 outside a refill shop where he is the first in line before it opens in Callao, Peru, early Tuesday, February 2, 2021. Ccasa said his family has one large tank and it gives about four hours of oxygen therapy. (Photo by Martin Mejia/AP Photo)

The sun begins to set over this rusty beachside mansion that has been left abandoned for more than 25 years in Thailand, June 2017. A deserted beachside mansion in southern Thailand has retained its beauty – despite no one living there for more than 25 years. In June this year abandoned photographer, Dax Ward, ventured to the Prachuap Khiri-Khan Province to capture the haunting attraction on camera. (Photo by Dax Ward/Barcroft Images)