During its most recent restoration, the paint layer structure of the five panel topographically exact view of the city of Zurich in the Swiss National Museum (Zurich) was examined. The two panels which depict the Grossmünster side of the river were found to have a different structure from that of the panels which depict the Lindenhof side of the river and the martyrdom of the patron saints of Zurich. A study of the sequence of the stages of the painting and overpainting led to the conclusion that the second layer (with the overpainted saints), which was set down shortly after 1566, was the most important layer. However, in 1936, this layer had beenremoved from the three panels depicting the Lindenhof side of the river. This posed the problem of relating the original paint layer to that of 1566. The problem was complicated by the fact that the colors above all the blue of the sky had discolored differently. See also 20-637. -- AATA