Omar Gamal, a 28-year-old pigeon keeper, stands next to his pigeon coop on his rooftop in the Egyptian capital's twin city of Giza on February 21, 2021, with the Pyramids of (R to L) Khufu (Cheops), Khafre (Chephren), and Menkaure (Menkheres) in the background. An ancient tradition handed down through the generations, the practice of domesticating pigeons stretches across borders from the banks of the Nile to north Africa and beyond, with people not only training birds for competitions, but also serving them up as a dining delicacy. (Photo by Khaled Desouki/AFP Photo)

Gorbea Natural Park is a protected area located between the provinces of Alava and Vizcaya in the Basque Country of northern Spain. Gorbea takes its name from its highest peak, the Gorbea (or Gorbeia) at 1,482 metres (4,862 ft) above sea level.

Sunset is seen through smoke from the Wallow fire June 8, 2011 in Springerville, Arizona. Hundreds of thousands of acres have burned in eastern Arizona prompting evacuations by residents. Smoke loomed over the twin towns of Eager and Springerville, home to about 7,000 people north of the fire. (Photo by Eric Thayer/Getty Images)

A worker prepares the “Cutter Head” of the Port Tunnel boring machine for attachment to the tunneling machine on September 1, 2011 in Miami, Florida. The $45 million machine is longer than a football field and about as tall as a four-story building and it will carve the twin tunnels connecting Watson Island and Dodge Island. The the new $1 billion Port of Miami tunnel is expected to be completed in May of 2014. (Photo by Joe Raedle/Getty Images)

Mount Etna erupts near Sicily, Italy on March 15, 2021. This is the thirteenth time in twenty-eight days. During the early evening of 14 March and the night between 14 and 15 March a strombolian activity at the Southeast Crater gradually increased, leading to a paroxysmal event which had its peak around 01:00 am, ash blown by the wind touched the south-southeast slope of the volcano reaching also Catania, the event ceased completely around 3:45, photo taken from Milo near Catania on March 15, 2021. (Photo by Salvatore Allegra/Anadolu Agency via Getty Images)

The National September 11 Memorial & Museum (branded as 9/11 Memorial and 9/11 Memorial Museum) is the principal memorial and museum commemorating the September 11 attacks of 2001, which killed nearly 3,000 people, and the World Trade Center bombing of 1993, which killed six. The memorial is located at the World Trade Center site, on the former location of the Twin Towers, which were destroyed during the attacks. The World Trade Center Memorial Foundation was renamed the National September 11 Memorial & Museum at the World Trade Center in 2007.

“Himalayan Dog”. This dog just appeared out of nowhere and followed us for an entire week during our trekking trip in the Himalayan outback. He always used to sleep in front of our tent and guarded us in the nights. When I decided to get up at 4 a.m. to climb the next 5000 m peak for sunrise he accompanied me as well. On the top he was sitting for the entire 30 minutes on this place looking straight into the countryside. Photo location: Ladakh, India. (Photo and caption by Sebastian Wahlhuetter/National Geographic Photo Contest)

A long exposure image shows star trails from the abandoned submerged orthodox church of St. Nicholas without roof, submerged in the Mavrovo Lake, near Mavrovi Anovi, North Macedonia, 17 March 2019. Constructed in 1850 and submerged in 1952 due to the construction of the hydro system Mavrovo, the church St. Nicholas continues to attract the attention of almost every visitor as it peaks from the water. (Photo by Georgi Licovski/EPA/EFE)