I am looking for another word or idiomatic phrase for "monument" that would not connote memorialization, but would connote that it is functions as a symbolic replacement for what it represents, more specifically, a demonstration of some future (or empty) promise.
E.g. In 1930s, Stalin built in Moscow 8 skyscrapers that were supposed to demonstrate socialist care for housing, but it did little to alleviate really-existing housing shortage; these houses were like monuments or idols (objects of worship) for the regime, distractions from reality with which Stalin could say: we have solved the housing crisis, let's move on. Another example could be Ceaușescu's metro in Bucharest in a country that was largely running on cart wheels up till the 1980s... It doesn't have to apply only to material structures, but also to institutions, artworks, etc.
Sample sentence: Rather than helping to solve the housing shortage, Stalin's skyscrapers functioned as _______ of/to/for an abstract socialist future.
P.S. I feel "window-dressing" does not really capture it