The library of the Technical University in Delft, The Netherlands, is located in the centre of the campus, adjacent to the main university auditorium which was designed in the 1960’s by renowned Dutch architects Van den Broek and Bakema. Its dominant concrete appearance provides a strong icon for the campus, making the relationship between the two buildings an important design criterion. To this end, a large sloping green space that is accessible to pedestrians only was designed to both act as a setting for the auditorium and the entrance to the library. At one corner the grassed surface elevates to form the roof of the main hall of the library. Both this green roof and the reduced external wall surface provide the Library with a sustainable quality as well as a comfortable internal environment. Wrapped around the building is a tilted glazed climate facade with an irregular pattern of horizontal mullions, which lend character to the building. A 40m cone pierces the roof, providing a source of light during the day and forming a beacon to the surrounding area when illuminated at night. Work and study spaces are situated in the main hall and the quieter interior of the cone, providing students with a choice of different atmospheres to work in. From the main entrance road into Delft, the full height and character of the library can be appreciated.