Sculpture
Three-dimensional artwork (carved, cast, welded, assembled, or built), the oldest and still the most common form of public art.
The word now stretches far past bronze and stone: light works, sound pieces, inflatables, and digital fabrication all get commissioned under "sculpture." What hasn't changed is that material choices drive lifetime cost. Bronze and granite age gracefully on a schedule of washing and waxing; painted steel needs repaint cycles; mixed-media and electronic works need a plan for component failure written before the ribbon is cut.
People often ask how a sculpture differs from a statue: every statue is a sculpture, but a sculpture is only a statue when it's a representational figure, a person or an animal. Abstract work is sculpture, never statuary.