Andrew Christian Peter Willatzen (after 1918, Willatsen) was born in Schleswig-Holstein in 1876 although he considered himself a Dane. He came to the U.S. in 1900 and first worked as a carpenter and then as a draftsman. Willatzen arrived at Frank Lloyd Wright's Studio in Oak Park, Illinois in 1902 where he became a valued apprentice. In 1907, after about three years of experience with Wright, he moved to Spokane and secured a position with Cutter and Malmgren. He was soon sent to the Seattle office to supervise the construction of the Seattle Golf & and County Club in 1908. In 1909, Willatsen formed a partnership with Francis Barry Byrne (1883-1967). The new firm began a series of homes adapting Wright's principles to the Northwest environment. Among these were the Clarke House, the Handschy House, Matzen House, Kerry Mansion, Maurer House, and McVay House. They also designed business, commercial, and industrial structures until Byrne left Seattle in 1913. In solo practice, Willatsen continued to design homes reflecting the Prairie idiom, including the Black House, Bellman House, Vogue House, Ramussen House, and Martin House. The 1910 design of the Sanitary Public Market Building began Willatsen's lifelong association with the Pike Place Market. He designed buildings in the Northwest vernacular until his "retirement" in the late 1940s. His last years were spent managing the apartment building he owned, studying philosophy, and producing an occasional design for a friend or old client. Willatsen died in 1974 at the age of 97.