The new Philological Library at the Free University of Berlin’s Dahlem site completes the renovation and restructuring programme of this 1973 complex, originally an open, flexible design with a deliberately unmonumental appearance. The library, which brings together the stocks of 11 different institutes, was built within the existing complex, at the wish of the client. Its bubble-shaped volume now stands as a separate building on the site of two former courtyards. It is connected to the adjacent buildings via two coloured lock-like gates. The library’s double-skinned shell is supported on a prefabricated tubular-steel space frame. Silver aluminium panels alternate with double-glazed windows on the outside, while a skin of white fibreglass covers most of the inside. This material softens the incoming daylight, diffusing it evenly through the space to create a calm, concentrated atmosphere. In the interior the various cantilevered floor decks stack up in the centre, accommodating bookshelves and providing space along their curved parapets for 600 reading desks. A light ditch surrounds the lower ground floor for better illumination. To keep the curve of the shell flat, the load-bearing frame is supported on the concrete cores either side of the central, open staircase.