This remarkable sculpture consists of 16 identical rats, all of them jet black, sitting side by side on their hind legs. They are arranged in a circle, with their upper bodies leaning slightly outwards and their front paws raised. The giant bodies, twice human size, tower above the visitor. Looking through the dense array of rodents, one sees that their tails are woven into an enormous, ordered knot. Their stance indicates that they are ready to attack, but the impulse is blocked by the tangling of their heavy tails, which renders them immobile. Thus the knotted tails form a centre, surrounded and guarded by the rats.

The inspiration for Rattenkönig dates back to 1989, when Fritsch was staying in New York. She was overwhelmed by the city, with its formations of soaring skyscrapers and plunging abysses. The rat king motif refers to a natural phenomenon – which is extremely rare and, as yet, not fully understood – involving young rats whose tails become intertwined in the nest, to a point where they can no longer extricate themselves. Sightings of these so-called rat kings have been reported since the late Middle Ages, when they were feared as harbingers of the Plague. In Fritsch's sculpture, the rat king evokes the image of New York as a Moloch, and alludes at the same time to German mythology.

After exhibiting the monumental work for a year at the Dia Art Foundation in New York, Fritsch also showed it at the Lyons Biennale in 1997 and the 48th Venice Biennale in 1999, shortly before its acquisition by the Emanuel Hoffmann Foundation. Finally, with the construction of Schaulager, it became possible to install the sculpture permanently in Basel.