Senator Barack Obama (D-IL) (R) stands in front of Senator Hillary Clinton (D-NY) as they arrive for U.S. President George W. Bush's annual State of the Union speech to a joint session of Congress at the U.S. Capitol in Washington in this January 23, 2007 file photo. Hillary Clinton announced her second run for the presidency on April 12, 2015 starting her campaign as the Democrats' best hope of fending off a crowded field of lesser-known Republican rivals and retaining the White House. (Photo by Larry Downing/Reuters)

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.

Two De Brazza's monkeys stand together at Port Lympne Wild Animal Park on June 21, 2011 in Hythe, England. Port Lympne has welcomed a host of new arrivals this year with wildebeest, colobus monkeys, gorillas and rhinos all adding to the current stock. Port Lympne and Howletts Wild Animal parks were set up by the late John Aspinall to protect and breed rare and endangered species and, where possible, return them to safe areas in the wild. The Aspinall Foundation which runs the parks also manages two gorilla rescue and rehabilitation projects in the central African countries of Gabon and Congo where they have successfully reintroduced over 50 gorillas to the wild. (Photo by Dan Kitwood/Getty Images)

Participants re-enact the “Battle of Five Armies” from J.R.R. Tolkien's novel “The Hobbit” in a forest near the town of Doksy, Czech Republic June 6, 2015. According to event organizers, hundreds of enthusiasts dressed as characters such as elves, dwarves, goblins and orcs from the book “The Hobbit” re-enacted the clash. (Photo by David W. Cerny/Reuters)

Migrants with a stick, stones and knife fight with each other after a brawl erupted over a place in an overcrowded train heading to the Serbian border at the train station in Gevgelija, The Former Yugoslav Republic of Macedonia, 14 August 2015. The number of migrants passing through Macedonia increases day by day, local sources said. From the beginning of the year to mid-June 2015, nearly 160,000 migrants landed in the southern European countries, mainly Greece and Italy, on their way to wealthier countries in Western and Northern Europe, according to estimates by the International Organization for Migration (IOM). (Photo by Georgi Licovski/EPA)

A street actor dressed as a devil frightens children in downtown Prague in Prague, Czech Republic, Monday, December 5, 2016. On the eve of St. Nicholas, Czechs traditionally celebrate by dressing up as Devils, Angels and St. Nicholas, and visiting children in their homes handing out small presents, coal, potatoes or other gifts. (Photo by Petr David Josek/AP Photo)

Migrants with a stick, stones and knife fight with each other after a brawl erupted over a place in an overcrowded train heading to the Serbian border at the train station in Gevgelija, The Former Yugoslav Republic of Macedonia, 14 August 2015. (Photo by Georgi Licovski/EPA/EFE)

A Polish girl and a boy throw water over each other on Wet Monday in Szczecin, northwestern Poland, 13 April 2020. Wet Monday is a Catholic celebration held on Easter Monday mostly in Poland, but also in the Czech Republic, Slovakia, Hungary and some parts of western Ukraine. Due to the lockdown it is forbidden to celebrate this holiday in public. (Photo by Marcin Bielecki/EPA/EFE)