The Guaranty Building, now called the Prudential Building, is an early skyscraper in Buffalo, New York. It was completed in 1896 and was designed by Louis Sullivan and Dankmar Adler.Sullivan's design for the building was based on his belief that "form follows function". He and Adler divided the building into four zones. The basement was the mechanical and utility area. Since this level was below ground, it did not show on the face of the building.