Los Angeles conceptual artist and CalArts instructor Michael Asher died Sunday at age 69 after a long illness, reported the L.A. Times.

"Few artists have had a larger role than Michael Asher in establishing Conceptual art within both art schools and museums," Kirsten Swenson wrote in Art in America in a May 2008 article ("If Walls Could Speak") about Asher's installation at the Santa Monica Museum of Art, for which he re-created the architectural framework for every temporary exhibition wall built there.

After participating in several landmark Conceptualist exhibitions in New York in the late '60s, including "Spaces" at the Museum of Modern Art and "Anti-Illusion: Procedures/Materials" at the Whitney Museum, Asher began teaching in the "post-studio" program at California Institute of the Arts (CalArts)in the early '70s. His classes were known for critique sessions, devoted to discussing student works, which could last over 12 hours.

Among his notable projects were his 1979 removal of Jean-Antoine Houdon's Neo-Classical bronze sculpture of George Washington from its place outside the Art Institute of Chicago, replacing it in a period gallery, and his removal of a wall of L.A.'s Claire Copley Gallery in 1974, revealing the gallery's offices to view.

For his contribution to the 2010 Whitney Biennial, Asher proposed that the museum remain open 24 hours a day for 7 days. Due to logistical limitations, the museum ended up staying open for three days. He won the $100,000 Bucksbaum Award, given to one artist in the show.