In 1960, he began creating stained glass windows for the synagogue of Hebrew University's Hadassah Medical Center in Jerusalem. Leymarie writes that "in order to illuminate the synagogue both spiritually and physically", it was decided that the twelve windows, representing the twelve tribes of Israel, were to be filled with stained glass. Chagall envisaged the synagogue as "a crown offered to the Jewish Queen", and the windows as "jewels of translucent fire", she writes. Chagall then devoted the next two years to the task, and upon completion in 1961 the windows were exhibited in Paris and then the Museum of Modern Art in New York. They were installed permanently in Jerusalem in February 1962. Each of the twelve windows is approximately 11 feet high and wide, much larger than anything he had done before. Cogniat considers them to be "his greatest work in the field of stained glass", although Virginia Haggard McNeil records Chagall's disappointment that they were to be lit with artificial light, and so would not change according to the conditions of natural light.