Waterloo's first YMCA was chartered in 1868, just three months after the incorporation of the city. This building, constructed in 1931, served the YMCA in Waterloo from 1932 to 1982, when the present Waterloo YMCA building opened at 669 South Hackett Street.

The Hannas purchased 120 acres at this site, the highest point between Prairie Rapids and the falls of the Cedar. Mary Hanna had seen the site from the river crossing. This was her "promised land." They built a cabin and lived here for the next eight years.

Mortimer Cleveland, an important local architect, designed the YMCA Building in the art deco style. It was built of reinforced concrete with stone and brick exterior walls. A new section was added in 1959. It is now on the National Register of Historical Buildings.

While the YMCA building is architecturally significant, the site is perhaps more important from a historical point of view. This was the heart of the Waterloo's mill district from the 1850s to the 1920s. The City Mill, Cedar mill, flourmill, saw mill 'and woolen Mill were among those located across the street or across the river. This was also the location of Prairie Rapids Crossing, the easily forded stretch of the Cedar River that gave the settlement its pioneer name.

It now houses business offices, health clubs and a restaurant.