A United States Air Force (USAF) F-15 fighter jet travels at low altitude through the “Mach Loop” series of valleys near Dolgellau, north Wales on June 26, 2018. The Mach Loop valleys, situated between Dolgellau and Machynlleth, are regularly used by the military for operational low flying training which can take place as low as 76 metres from the nearest terrain. The USAF regularly use the loop to practice low-altitude flight, which confuses radar systems. (Photo by Oli Scarff/AFP Photo)

A worker stands by a historic building as it is moved down the block on wheels on New York Avenue to make way for a new construction July 28, 2014 in Washington, DC. A team from Expert House Movers have been moving the historic building near 4th Street which is one of the largest structures in the DC area to be moved. (Photo by Brendan Smialowski/AFP Photo)

Aeroflot employees with a puppy at the canine service of Aeroflot at Sheremetyevo International Airport in Moscow Region, Russia on October 2, 2020, that has started to train service dogs to detect COVID-19 in people. (Photo by Vladimir Gerdo/TASS)

A couple walk in the Retiro park in Madrid on November 17, 2020 as a thick fog falls on the Spanish capital. (Photo by Gabriel Bouys/AFP Photo)

A person watches the sunrise from the Edge observation deck at Hudson Yards on the first day of spring on March 20, 2021 in New York City. (Photo by Noam Galai/Getty Images)

An inmate (L) tends to a fellow prisoner while performing ear candling during an alternative therapy session as part of the ACUDA programme, at a complex of ten prisons in Porto Velho, Rondonia State, Brazil, August 27, 2015. Ear candling, which involves inserting a hollow cone-shaped device into the ear canal and lighting the exposed end, is believed by practitioners to draw out earwax. According to ACUDA the therapy is beneficial for the inmates' emotional health. (Photo by Nacho Doce/Reuters)

Children react after what activists said was shelling by forces loyal to Syria's President Bashar al-Assad near the Syrian Arab Red Crescent center in the Douma neighborhood of Damascus May 6, 2015. (Photo by Bassam Khabieh/Reuters)

Sudanese fishermen check their boats and nets before they row through the waters of Nile River near Jebel Aulia, Sudan, May 3, 2019. (Photo by Umit Bektas/Reuters)