the wrigley building was built to house the corporate headquarters of the chicago-based wrigley chewing gum company (founded by william wrigley jr. in 1891). when ground was broken for the wrigley building in 1920, there were no major office buildings north of the chicago river. the michigan avenue bridge, which spans the river just south of the building, was still under construction. the land was selected by mr. wrigley for the headquarters of his company. the terra cotta-clad building was designed by the notable architectural firm of graham, anderson, probst & white using the shape of the giralda tower of seville's cathedral combined with french renaissance details. the two towers are of differing heights, with the south tower rising to 30 stories and the north tower to 21 stories. on the south tower is a gargantuan terra cotta clock with faces pointing in all directions (four sides). each face is 19 feet 7 inches in diameter. the building is clad in an off-white glazed terra-cotta executed by the northwestern terra cotta company, chicago, ills. the entire building is periodically hand washed to preserve or uphold the cream-colored terra cotta glaze. in 2014 urban remains salvaged the exterior prairie style ornamental cast iron wall sconces from the wrigley chewing gum factory (housed in the heart of the central manufacturing district) located on the south side of chicago. demolition of the wrigley gum factory complex was awarded to heneghan wrecking in december of 2014, who has collaborated on large scale projects with urban remains for over a decade.