In 1890, the Federal government decided to design all Federal buildings to reflect the heritage of the communities in which they were located. A post office in Saginaw, Michigan was the first building in the United States to be constructed in accordance under these guidelines. In 1896, after years of negotiation, the Federal government appropriated $100,000 for the construction of a new post office on the city's east 
side.
"The first settlers in the valley located therein in 1858; they were mostly of French origin....; their avocation [was] chiefly trading with the Indians, hunting and fishing. The post office at Saginaw is accordingly French in style, the corner towers being suggestive of the defensive features of frontier life, while the carving of the pinnacles and finials was suggested by the fauna and flora of the neighborhood."
By the 1930's Saginaw's postal needs had outgrown the building's capacity. At first the Federal government planned to replace the Castle with a "contemporary" structure. Concerned citizens persuaded officials to remodel the building rather than demolish it.
Carl Macomber, a local architect, was commissioned to enlarge and update the building. The original chateau architecture was maintained during the extensive renovation in 1937 but there were changes. A major tower, including a circular staircase, was sealed off. A new lobby and a new stairway room have been reopened.