The new National Library of the Czech Republic will be located in Letna park, one of the largest and most well-known green oases in Prague. From the town planning point of view contest participants had a carte blanch, but the technical enquiry was of high complexity – they complex of 6 thousand sq m apart from books ever published in the Czech Republic (in paper or digital) must house numerous reading rooms and conference halls, lecture halls, a museum. Besides, the exclusive requirement was the possibility to extend the building after 2040 at least by one third. The architects considered the book as a kind of code access to which have those who have particular knowledge. “Nowadays everything is available and it leads to devaluing of information, - say the authors, and such natural code like a book text, becomes a kind of barrier to pass in order to extract the massage” At that codes are simple and difficult , to get the most secret of them it can take a lifetime... So the access system of different levels is the key in the library image. The site has considerable ground drop and the architects offered to place the complex onto the platform earthed at different levels. For example, one of its corners is completely under the ground, its north-east side is on the contrary raised over the ground. The library would balance on the hill and the platform would become a view platform, integrating different constructions.