California-born, New York-based Walter De Maria trained as a painter but soon turned to sculpture, creating early Minimalist works like sparely constructed wooden boxes while exploring media such as performance, film, and music (he was a proto-member of the Velvet Underground). He was also at the forefront of the 20th century's Land Art, Conceptual Art, and installation art movements, creating seminal works like The Lightning Field (1977), a series of 400 stainless steel poles arranged in a grid in the New Mexico desert; the viewers’ perception of the work changes with the time of day and atmospheric conditions.