I want to know the answer to the following question:
When did figure wall mosaics become the highest form of artistic expression?
All the background I'm provided with is that "The Roman church of Santa Costanza, which served as a mausoleum for one or more of the Imperial family, has both religious mosaic and decorative secular ceiling mosaics on a round vault, which probably represent the style of contemporary palace decoration.". Is that enough to answer the question?
Answer: no