Mayor Richard Daley is credited with creating this prominent new civic center that is considered the most ambitious public architectural project in Chicago since the Columbian Exposition in 1893. Millennium Park is a portion of the larger Grant Park, the "front lawn" of downtown Chicago and one of the larger public parks in metropolitan Chicago and is a showcase for postmodern architecture. It features the McCormick Tribune Ice Skating Rink, Peristyle at Wrigley Square, Joan W. and Irving B. Harris Theater for Music and Dance, AT&T Plaza, Lurie Garden, Chase Promenade and Trees in Millennium Park. There are three major artistic highlights: Cloud Gate, Crown Fountain and the Jay Pritzker Pavilion. Millennium Park is often considered the largest roof garden in the world, having been constructed on top of a railroad yard and large parking garages. Of its total 24.5 acres of land, Millennium Park contains 524,358 square feet of permeable area (12.04 acres).