The Centennial Building was completed in the same year as Custer's Last Stand and was named for the nation's 100th birthday. From 1918 to 1955, it was occupied as a pool hall and cigar store, and tobacco was believed to have been hung to dry in the basement, where tobacco posters can still be seen. In 1992, a new owner painted part of the building "Frog Green," provoking strong community reaction, drawing statewide attention, and eventually prompting a local ordinance on historic buildings known at the time as "The Green Building Ordinance." Interior renovations in 2017 uncovered a wall displaying dozens of signatures from Oskaloosa residents dating back as far as 1880, and the wall was incorporated into the design for public viewing.