In 1949-50 Isamu Noguchi traveled the world to study the sculpture of past civilizations, and he was especially impressed with the large urban sites of public assembly. These he viewed as sculpted spaces for social ritual, places in which sculpture performed an important function in everyday life. He had designed such a space in an ambitious 1945 proposal for Jefferson Memorial Park in Saint Louis, Missouri, a plan based on the Native American Great Serpent Mount in Ohio. But it was not until the 1970s, when Noguchi designed the eight-acre Philip A. Hart Plaza in Detroit (1972-79), that he was able to build a major urban project. Noguchi designed two more large urban projects: Bayfront Park in Miami, Florida (28 acres, begun 1980), containing a monument to the astronauts who perished in the Challenger disaster, and Moere Numa Park in Sapporo, Japan (400 acres, begun 1988), both of which remain under construction. Although Noguchi also completed many gardens, playgrounds and sculpture gardens in urban areas, none match the scale of these grand examples of what the artist called" the sculpture of spaces".