Rachel Whiteread

Rachel whiteread the fourth plinth

Think is quite clever.

Complete opposite to the original solid structure of the two rectangles one smaller than the other

Used a much more fragile material glass.

This emphasises its contrast

Rachel Whiteread is an English artist, best known for her sculptures, which typically take the form of casts. She won the annual Turner Prize in 1993 the first woman to win the prize.

Many of Whiteread's works are casts of ordinary domestic objects and, in numerous cases, the space the objects do not inhabit (often termed the "negative space") — instead producing a solid cast of where the space within a container would be; particular parts of rooms, the area underneath furniture, for example. She says the casts carry "the residue of years and years of use". Whiteread mainly focuses on the line and the form for her pieces.
Unlike many other Young British Artists who often seem to welcome controversy, Whiteread has often said how uncomfortable she feels about it. On 24 May 2004, a fire in a storage warehouse destroyed many works from the Saatchi collection, including, it is believed, some by Whiteread.