The synagogue was in very dilapidated condition when I saw it first in 1990. I was told it had been used as a matzo factory after WW2. In Virtually Jewish, I quoted Monika Krajewska, who first visited the Kupa synagogue in the 1970s, when it was used as a warehouse:
"We stared at the walls, with their paintings: the lions, the deer, all the things that relate to Jewish biblical tradition of synagogue decoration. And there were workers who were just installing additional shelves; they were making holes in the lion's nose, in the instruments of the Levites painted on the ceiling."
Among the decorative elements discussed by Sam is that of curtains painted around the Ark -- in the picture below, Alan Bern, on piano, accompanies Lorin Sklamberg singing in front of the Ark of the Kupa at the Jewish Culture Festival in 2004.
Photo (c) R. E. Gruber
A second decorative element that interests me a lot is the painting around the Ark, which is a large and impressive Baroque construction. On the wall behind the projecting stone Ark is painted a large red curtain, drawn apart just above the apex of the Ark. Of course this too, can have Temple associations, since a curtain in the Temple hung before the entrance of the Holy of Holies. Here, though, the curtain is hung behind the Ark, and it is open. What does it mean? Is it an earthly curtain, intended to create the illusion of greater synagogue space? Is it a symbolic curtain, representing either Temple or perhaps the revelation of the Torah? Or perhaps is it a curtain allowing a glimpse form this world into another? It could be all these things, or none. I’m not going to decide. But since I’m looking I am seeing these curtains almost everywhere - and they are one of the favorite European (or Polish) synagogue decorative devices carried over by immigrant artists from the old world to the new. I'm still looking for some contemporary user - a rabbi or congregant - who commented on their position and use.
I, too, have seen painted curtains around Arks in synagogues in several countries. Here is a short slide show of some of them: you can see the variety of construction of the Ark itself, as well as the way in which the curtain motif is used.