In Rome, Nero and his architects used mosaics to cover some surfaces of walls and ceilings in the Domus Aurea, built <answer>64 AD</answer>, and wall mosaics are also found at Pompeii and neighbouring sites. However it seems that it was not until the Christian era that figural wall mosaics became a major form of artistic expression. 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.
When was the Domus Aurea constructed?
64 AD