A woman takes part in a four-minute flash mob pillow fight at the Old Town Square in Prague, Czech Republic, December 22, 2016. (Photo by David W. Cerny/Reuters)

A participant runs through colored powder as she takes part in the Get Rainbowed run in Prague May 23, 2015. Get Rainbowed is a five-kilometre race with the aim of promoting a healthy lifestyle. (Photo by David W. Cerny/Reuters)

An enthusiast dressed as a zombie takes part in the annual Zombie Walk festival in Prague June 1, 2013. (Photo by David W. Cerny/Reuters)

A woman poses for a photo in an almond plantation near Kiryat Gat, Israel February 17, 2018. (Photo by Amir Cohen/Reuters)

The Clementinum (Klementinum in Czech) is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic. In 2005, the Czech National Library received the UNESCO Jikji prize (Memory of the World).

This picture taken on March 21, 2015 shows a couple kissing in front of blooming cherry blossoms in Wuhan in central China's Hubei province. The cherry blossoms, now in full bloom, attracted tens of thousands of visitors, local media reported. (Photo by AFP Photo/Stringer)

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.