A cat sits on the empty Great Wall on February 23, 2021 in Beijing, China. Affected by the new coronavirus (COVID-19), the number of visitors to Mutianyu Great Wall in 2020 dropped by about 60%. (Photo by Lintao Zhang/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)

Empty gloves are seen at the side of a tray of Maryland Blue Crabs at Maine Avenue Fish Market which is the United States oldest fish market in continual operation since 1805, in Washington, U.S., May 6, 2019. (Photo by Clodagh Kilcoyne/Reuters)

A woman walks with her daughter through an empty street on April 27, 2020 in Malaga, Spain. Since April 27 children under 12 are allowed to come and go from their homes more freely. Spain has had more than 209,000 confirmed cases of COVID-19 and over 23,000 reported deaths, although the rate has declined after weeks of lockdown measures. (Photo by Daniel Perez Garcia-Santos/Getty Images)

In this March 20, 2016 photo, Maj. Mohammed Hussein, an officer with Iraq's elite counterterrorism forces, shows a photo of a slain Islamic State group militant still wearing in a suicide vest, taken during fighting that freed the city of Ramadi from IS control earlier this year. As they fled, the militants destroyed some buildings and booby-trapped others with explosives, leaving behind an empty prize for government forces retaking the city. (Photo by Maya Alleruzzo/AP Photo)

In this Saturday, May 7, 2016 photo, Afghan refugee Shazia Lutfi, 19, peeks through the door of her room at the former prison of De Koepel in Haarlem, Netherlands. The government has let Belgium and Norway put prisoners in its empty cells and now, amid the huge flow of migrants into Europe, several Dutch prisons have been temporarily pressed into service as asylum seeker centers. (Photo by Muhammed Muheisen/AP Photo)

Syrian dancer and choreographer Yara al-Hasbani performs a dance on the empty Trocadero square in front of the Eiffel tower in Paris on April 22, 2020, on the 37th day of a strict lockdown in France to stop the spread of COVID-19 (novel coronavirus). (Photo by Sameer Al-Doumy/AFP Photo)

An empty beer bottle stands in front of the buildings of the banking district in Frankfurt, Germany, Friday, May 21, 2021. All people gathering on the square for drinks and food left when the police started checking if they are abiding by the coronavirus restrictions. (Photo by Michael Probst/AP Photo)