Hot air balloons fly over the sky in Chiang Mai province, northern Thailand, December 6, 2014. The two-day International Balloon festival 2014 featuring balloon pilots from Germany, Spain, Netherlands, Britain, and Czech Republic is held on December 06-07 2014 to celebrate Thai King Bhumibol Adulyadej's 87th birthday and also aimed to promote the tourism industry in Chiang Mai northern city. (Photo by Pongmanat Tasiri/EPA)

A relic hunter dubbed “Indiana Bones” has lifted the lid on a macabre collection of 400-year-old jewel-encrusted skeletons unearthed in churches across Europe. Art historian Paul Koudounaris has hunted down and photographed dozens of gruesome skeletons in some of the world's most secretive religious establishments. Photo: Albertus in the church of St George in Burgrain, Germany. Incredibly, some of the skeletons, which took up to five years to decorate, were even found hidden away in lock-ups and containers. (Photo by Paul Koudounaris/BNPS)

A participant poses with his laptop during the 33rd Chaos Communication Congress on its opening day on December 27, 2016 in Hamburg, Germany. The annual event is bringing together 12,000 computer hackers and activists who will meet over the next four days to share expertise and discuss topics related to the society and the digital world. (Photo by Morris MacMatzen/Getty Images)

Russian soldiers rehearse ahead of a forthcoming parade on Red Square in Moscow on November 5, 2017 The event will take place on November 7, marking the 76 th anniversary of a 1941 parade, when Red Army soldiers marched past the Kremlin walls towards the front line to fight Nazi Germany troops during World War Two. (Photo by Mladen Antonov/AFP Photo)

Participants dressed in historical clothing ride high-wheel bicycles during a bicycle ballet event at Schloss Karlsruhe palace during the 2017 International Veteran Cycle Association (IVCA) rally to celebrate the 200th anniversary of the bicycle on May 27, 2017 in Karlsruhe, Germany. Karl Drais, a German inventor, built and tested the first bicycle, called the Draisine, that ran without pedals in 1817. (Photo by Alexander Scheuber/Getty Images)

Both men and women dressed as singer Kate Bush from her 1978 video to her song “Wuthering Heights” dance in a brief rehearsal before seeking to create a new world's record for the most people dancing in costume to the song at once at Tempelhofer Feld park on July 16, 2016 in Berlin, Germany. While a precise account was unavailable just after the event, a calculated estimate put the number of dancers at between 400 and 500, well above the previous record set in 2013 in Brighton, UK of 300. (Photo by Sean Gallup/Getty Images)

Police officers escort people from inside the shopping center as they respond to a shooting at the Olympia Einkaufzentrum (OEZ) at July 22, 2016 in Munich, Germany. According to reports, several people have been killed and an unknown number injured in a shooting at a shopping centre in the north-western Moosach district in Munich. Police are hunting the attacker or attackers who are thought to be still at large. (Photo by Joerg Koch/Getty Images)

Spot, a robot with dog-like movements, walks past a dog in Cathedral Square in Erfurt, Germany on April 20, 2021. Security service provider Ciborius, a provider of robotic security solutions with artificial intelligence, presented its artificial employee with high-resolution 360-degree all-round camera, ultra-bright LED light and a light detection system on Domplatz. (Photo by Michael Reichel/dpa)