Relief sculpture is an artwork that projects out from a background surface. One side is flat with the artwork being on a wall or other flat background, and the other side has dimension like a sculpture.
The ancient Greeks used relief sculpture to decorate their buildings.
The ancient Romans also made relief sculptures. This Roman relief sculpture is on a sarcophagus, which is a coffin-like funeral box.
Ghiberti’s gilt-bronze doors of the Florence Baptistery are famous relief sculptures.
This bronze relief sculpture in Boston is a memorial to a Civil War regiment and commander.
Louise Nevelson
American abstract sculptor Louise Nevelson was known for her relief pieces created from found pieces of wood. She usually finished these sculptures in a monochromatic hue (one color).
Nevelson’s sculptures are wall-like relief collages with found objects such as chair legs and abstract shapes.
YouTube video - Dry Wall Art Sculpture [shows the whole process-could skip parts] (5:46 min.)