Alexander Calder is best known for his mobile sculptures composed of abstract shapes that move through space. Calder was born in 1898 in Philadelphia area into a family of artists (his father and grandfather were sculptors). He is most well known for his innovation in the area of movable suspended metal plates and wire assemblies that are activated in space by drafts. Visually fascinating and moving, these sculptures, as well as their monumental external stabilizers in bolted sheet metal, which only involve movement, make Calder one of the most recognizable and appreciated of all modern artists.