Ulm Municipal Library (glass pyramid)

In 1998 Ulm's municipal library held some 310,000 media items, of which barely a third could be placed on open shelves in very cramped premises; the rest was kept in compact storage. The city council therefore decided to build a new central library directly next to the town hall, on a site used until then as a car park between the Vestgasse, the Kronengasse and the Postgasse, whose gap dated from the last winter of the war, in 1944.

The international competition launched in 1998 called for a free-standing building that would set the library clearly apart from the buildings of the old town. The scheme ranked first, a slab by the Cologne firm Minkus & Wolf nicknamed the "battering ram", met with strong protests from the people of Ulm. The city set it aside, as it did the second prize by Volker Kurrle of Stuttgart, in favour of Böhm's glass house, ranked lower, which won the commission after being reworked. Construction took three years and the library was completed in 2004.

At first glance the library looks like a crystalline pyramid; in fact it consists of two volumes: an inverted stepped pyramid, partly buried and fully glazed, crowned by a steep pyramidal glass roof. The upper floors project outwards like a half-timbered house, then the building narrows into a pyramid. The plan is square. The skeleton frame, on a 6.6 m grid, leaves few walls; they were built in fair-faced concrete with rough formwork, in contrast to the smooth glass skin marked by fine horizontal lines. The building has nine levels.

From the third floor upward a walk-in double façade acts as a climate buffer. Large ventilation flaps prevent overheating in summer, a movable textile blind sits between the two skins, and the mass of the structure is cooled by night air.

At the centre an open spiral staircase of red-lacquered steel winds around a double lift. The screen workstations cluster around this core, while those at the façade look out over the city and the Alps. On the ceiling of the reading café, visible from below, a painting by Gottfried and Markus Böhm seems to extend the staircase to infinity: Gottfried Böhm designed it and his son Markus carried it out. With the Weishaupt museum, the savings bank and the Münstertor, the building forms the "Neue Mitte Ulm".

It is the city's central library. When it opened in 2004, the ground floor held lending and the information area, the children's library and the literature sections occupied the levels above, and a reading café with a gallery took up the fifth floor; the reading café is still at the top of the building.

The library stands at Vestgasse 1 in the old town and is open Tuesday to Saturday. From the reading café, high up in the building, the view takes in the old town and Ulm Minster.