I’ve walked by this curious old building a few times, and always paused to ponder its origin, its purpose, and its sad condition (never seen in this prim part of town). It sits snugly between a posh residential neighborhood and the focal point of three campuses: ETH, the University of Zürich (UZH), and the UZH hospital. Clearly, it once had a walk-up counter where one could arrange for the fabrication of chemical/technical apparatus.
Puzzled, a little Googling lead me to a brochure a local historical society wrote about this building. From what I can glean from that brochure (in German), this workshop was built in 1863 next to a small house, home to several generations of plumbers. The later generations apparently specialized in scientific apparatus as well as home plumbing solutions (Wasch & Badeeinrichtungen – wash and bathroom furnishings). After decades of disrepair, the property was protected under a local archaeological ordinance, purchased by the city, then restored into beautiful shape. It was left unused, however, and sadly became the target of graffiti vandals. It now appears likely to be demolished when the hospital next needs to expand. The adjacent house is now used by ETH as a daycare facility.