A bunker at aformer Swiss artillery fortress called Heldsberg stands near the town of St. Margareten, Switzerland March 22, 2015. Heldsberg fortress, located on the Swiss-Austrian border near the River Rhine and Lake Constance was built from 1938 to 1940 and remained in military use until 1992. Since 1993 it is open to the public as Fortress Museum Heldsberg. (Photo by Arnd Wiegmann/Reuters)

Festival goers splash through a muddy puddle at Worthy Farm in Somerset, on the third day of the Glastonbury music festival June 27, 2014. (Photo by Cathal McNaughton/Reuters)

Mercury and Maia, fueled and overhauled, are waiting in the Tay at Dundee, for favorable weather to start the flight to the Cape, a distance of 6,370 miles. The composite machine moored in the Tay River, at Dundee, on September 23, 1938. (Photo by AP Photo)

“Be prepared” is the motto of petite Doris Sherrell, vocalist and dancer with “Blackouts of 1942”. In the event of a bombing, the young lady had her social security number tattooed on one leg by artist Jack Julian, and address placed on the other limb for means of identification in Los Angeles, September 29, 1942. (Photo by AP Photo)

A deer walks across a pedestrian crossing in Nara, Japan, Thursday, March 19, 2020. More than 1,000 deer roam free in the ancient capital city of Japan. Despite the town's tourism decline, these wild animals are doing just fine without treats from tourists, according to a deer protection group. (Photo by Jae C. Hong/AP Photo)

EMT Christian Amoroso, wearing personal protective equipment (PPE), pauses while unloading COVID-19 patients at the Montefiore Medical Center Wakefield Campus on April 06, 2020 in the Bronx borough of New York City. A specialized bus known as a Medical Evacuation Transport Unit (METU), caries infected patients on stretchers and benches between hospitals. (Photo by John Moore/Getty Images)

A security officer looks at a scanning screen for checking passengers' temperature at the Istanbul Airport in Istanbul, Turkey, on June 9, 2020. Technology and innovation will top the precautions of Turkey's biggest airport Istanbul Airport against the COVID-19 in the post-pandemic era, according to the management of the airport. The management on June 9 presented their final preparations and measures taken against coronavirus while Turkish airline companies are preparing to resume their international operations the next day. (Photo by Yasin Akgul/Xinhua News Agency via Getty Images)

Sikh Nihang's Singh (Sikh warriors) walk along the empty Heritage Street after strict lockdown norms for weekends and public holidays were imposed as a preventive measure against the COVID-19 coronavirus, in Amritsar on June 13, 2020. (Photo by Narinder Nanu/AFP Photo)