Libraries are usually drawn in plan. You see the stacks as a comb, the reading room as a clearing, the desk as a gate. The Bibliothek am Hang is the rare library that can only be understood in section, because the section is the building.
The site slopes nine metres from the street to the river path. Rather than level it, the architects, a young office called Atelier Lenz, let the slope in. The entire interior is a single stepped floor that descends through the building in risers of forty centimetres, each riser deep enough to hold a shelf, a bench, or both.1Footnote 1: Forty centimetres is too high for a comfortable stair, which is deliberate; it forces a landing between every step, and landings are where people stop and read. There are no storeys. Asked how many floors the library has, the head librarian answers, after some thought, “about twenty-two.”
The reading experience is unlike anything in a conventional stack. You arrive at street level among the newspapers and periodicals. As you descend, the subjects follow a loose sequence: current affairs, then history, then the arts, then fiction, until the lowest terrace, almost at the river, holds the children’s books, where the glazing is lowest and the water is visible through it.2Footnote 2: The sequence was the librarians’ idea, not the architects’. It inverts the usual placement of children’s sections near the entrance, and the staff report fewer abandoned picture books as a result.
Because you are always a little above or below the next shelf, you see spines you would never have walked to. Browsing becomes a kind of descent, a drift. The librarians call it the slide. Circulation of mid-list fiction, the books that neither sell nor are assigned, has risen by a third since the building opened.
Structurally, the library is a timber roof on two concrete walls. The stepped floor is a single poured ramp with timber treads bolted on; the shelving is fixed to the risers and acts as a guardrail. The roof is pitched to follow the slope roughly, so that the ceiling height stays nearly constant as you descend, around 3.4 metres, except at the top where it opens up into a double-height entrance.3Footnote 3: The asymmetric pitch also sheds snow toward the river side, away from the street entrance, which matters in St. Gallen more than it would in most Swiss cities.
Accessibility was the obvious objection, and the answer is a lift that stops at four of the terraces and a long, gentle ramp along the north wall for the rest. Wheelchair users describe the ramp as the better route: the stacks are at eye level and the river appears gradually instead of all at once.
It is a small building, 1,400 square metres, and it will not be copied often; most sites are flat. But it makes an argument any library could use. A collection is not a grid. It is a slope, and people should be allowed to slide down it.