Nazi dictator Adolf Hitler greets supporters at a May Day gathering in the Olympic Stadium, Berlin. (Photo by Keystone). 1st May 1938

A reveller walks through the streets in the early hours during traditional May Day celebrations in Oxford, Britain, May 1, 2015. (Photo by Dylan Martinez/Reuters)

Students from the University of St Andrews jump into The North Sea, as a good luck tradition before exams start on the East Sands in St Andrews, Fife, Scotland on May 1, 2018. (Photo by Derek Allan/Alamy Live News)

A protester dressed as a clown holds an umbrella over a Swiss police officer on a motorbike during a May Day demonstration in Zurich, Switzerland on May 1, 2017. (Photo by Arnd Wiegmann/Reuters)

A Cambodian man sells shoes on a motorized cart travelling along a street in Phnom Penh, Cambodia, 30 April 2020. Cambodian authorities are enforcing strict traffic rules in an effort to cut down traffic accidents on the road as a new land traffic law will go into effect in the beggining of of May 2020. (Photo by Mak Remissa/EPA/EFE)

A police officer wearing a Balinese traditional mask, called celuluk, performs as the new coronavirus during a campaign to wear masks as a precaution against the virus outbreak at a market in Bali, Indonesia, Thursday, May 14, 2020. (Photo by Firdia Lisnawati/AP Photo)

Shiite Muslims gather, albeit in fewer numbers due to the COVID-19 pandemic, at the Imam Ali shrine in the central Iraqi holy city of Najaf late on May 16, 2020, to mark Lailat al-Qadr, a night in the holy month of Ramadan during which the Koran was first revealed to the Prophet Mohammed in the seventh century. Worshippers placed copies of the Koran on their heads to convey veneration during the overnight prayers in a centuries-old ritual, as they pleaded to God to rid them of the ongoing novel coronavirus pandemic. (Photo by Haidar Hamdani/AFP Photo)

Clarice Hui and her Corgi dog Padfoot enjoying the hot weather in London Fields park, east London on May 19, 2020, after the introduction of measures to bring the country out of lockdown. (Photo by Yui Mok/PA Images via Getty Images)