Third annex 1976–1982 Book Tower
The foundation stone for the third annex is laid in 1977, and the so-called “Book Tower” (Bücherturm) is inaugurated in 1982. This storage tower made of reinforced concrete (architect: Arnd Schultheiss) consists of a core 55 metres in height and five storage segments, has 14 floors and nine mezzanine floors, and provides space for around five million volumes. As an engineering structure, it was built using the slipform construction method, while its cuboid shape and direction reflect the high-rise buildings on the other side of the street rather than the historic building complex itself.