Looking at the enterance of the Clementinum, one could notice the Baroque archetecture and not think much of it. But the surprises of this building is that it is the second largest complex in Prague next to Prague Castle. This building covers an impressive 20,000 square metres.
Dating back to the 11th century, the Clementinum serves as the National Library. This historical complex building began as a chapel in honor of Saint Clement. Over the centuries the use of the Clementinum has changed drastically. Beginning as a chapel, to a monastery, to a college, to the library of Charles University and finally to the Clementinum in 1654. However, in 1654, all of its past purposes were still present. The Clementium served as an observatory, library and university by Maria Theresa of Austria. Finally in 1781 the Clementium had its final purpose as the home of the National Library.