Founded in 1140 by Prince Vladislav II, Strahov Monastery is a large, impressive building located at the back of Petrin Hill and Prague Castle. This elevated area of the city offers visitors a calm oasis, somewhere to stroll around, enjoy views over the Lesser Town (and indeed the whole of Prague), and to visit one of the city's finest churches. Strahov Monastery, and its surrounding area, has a serene, meditative quality, however its library is its most important feature, which comprises one of the oldest monastic collections in the country. The library is located in the theological and philosophical halls, and is over 800 years old. Despite ransacking by invading armies, it holds 16,000 books.