Participant wearing medieval costumes perform during an annual re-enactment of a battle near the village of Libusin, Czech Republic, April 23, 2016. About 2000 enthusiasts have come to simulate the medieval battle during the 24rd annual swordsmen gathering in Libusin village. (Photo by David W. Cerny/Reuters)

Participants wearing historical attire compete on historical high wheel Penny Farthing bicycles in the traditional 'One Mile Race' at Letna Park in Prague, Czech Republic, November 7, 2015. The meeting of Penny Farthing bicycles is taking place for the 22th time. (Photo by Filip Singer/EPA)

A competitor solves a Rubik's cube using his feet as he prepares for the Rubik's Cube European Championship in Prague, Czech Republic, July 15, 2016. (Photo by David W. Cerny/Reuters)

A child looks at a reveller dressed as devil on the eve of Saint Nicholas Day in Prague, Czech Republic on December 5, 2022. (Photo by David W. Cerny/Reuters)

Participants dressed as characters such as elves, dwarves, goblins and orcs from the J.R.R. Tolkien's novel “The Hobbit” re-enact the “Battle of Five Armies” in a forest near the town of Doksy, Czech Republic, June 4, 2016. Several hundred people arrived in the forest to re-enact the famous battle from Tolkien's novel that was published for the first time in 1937. (Photo by David W. Cerny/Reuters)

Switzerland's Belinda Bencic celebrates after defeating Czech Republic's Marketa Vondrousova during their Tokyo 2020 Olympic Games women's singles tennis final match at the Ariake Tennis Park in Tokyo on July 31, 2021. (Photo by Yara Nardi/Reuters)

Greece's Apostolos Angelis (L) and Austria's Felix Leitner compete during the men's 20 km individual event of the IBU Biathlon World Championships in Nove Mesto, Czech Republic on February 14, 2024. (Photo by Joe Klamar/AFP Photo)

The Prague astronomical clock, or Prague orloj, is a medieval astronomical clock located in Prague, the capital of the Czech Republic. The clock was first installed in 1410, making it the third-oldest astronomical clock in the world and the oldest one still working.