The idea for the pavilion for the annual book fair of Madrid was inspired by a simple variation on the theme of writing. The principal functions of reception and exhibition are hosted in a single glass volume of 25x5x5 metres, with an outside skin entirely composed of wooden letters serving as a distinctive and evocative permeable membrane. The individual letters are anchored to a steel substructure; the low-tech system allows visitors to modify the surface by inviting them to 'overwrite' and revise the text.