The Polish-born American architect Daniel Libeskind (born 1946) is one of the most prolific of contemporary museum architects, He was an academic before he began designing buildings, and was one of the early proponents of the architectural theory of Deconstructivism. The exterior of his Imperial War Museum North in Manchester, England (2002), has an exterior which resembles, depending upon the light and time of day, huge and broken pieces of earth or armor plates, and is said to symbolize the destruction of war. In 2006 Libeskind finished the Hamilton Building of the Denver Art Museum in Denver Colorado, composed of twenty sloping planes, none of them parallel or perpendicular, covered with 230,000 square feet of titanium panels. Inside, the walls of the galleries are all different, sloping and asymmetric. Libeskind completed another striking museum, the Royal Ontario Museum in Toronto, Ontario, Canada (2007), also known as "The Crystal", a building whose form, resembles a shattered crystal. Libeskind's museums have been both admired and attacked by critics. While admiring many features of the Denver Art Museum, "The New York Times" architecture critic Nicolai Ouroussoff wrote that "In a building of canted walls and asymmetrical rooms—tortured geometries generated purely by formal considerations — it is virtually impossible to enjoy the art."