The new building for the town and school library is both an extension of the school built in 1970 as well as a public library for the citizens of Kelsterbach. While solid parts of the building take over characteristics of the existing school in terms of material and proportion, a roof in form of a butterfly represents the new public library. The solid structure incorporates facilities such as emergency stairs, toilets, storage, administration, and the reception. The open, light flooded spaces comprise book shelves and reading areas. Ground floor and first floor are visually connected by open spaces and open up to the outer space between school and library.