Polk County built its first courthouse in 1847 for $2,015. The brick building measured . After the second courthouse was completed, this first building was sold to a church for $800. It later became the Union Depot serving the
Wabash and the Des Moines Union Railroads. The second courthouse was built in 1858 for $94,000. The two-story
Italianate structure, designed by J.C. Farrand, featured a dome. The building measured and the dome rose to a height of . This building was enlarged in 1866. The present courthouse was built in 1906 on the same square as the previous courthouse. It was built for $750,000 in the
Beaux-Arts style. Measuring , the rectangular structure was designed by the Des Moines architectural firm of
Proudfoot & Bird. It is one of the largest county courthouses in the state, and one of the most architecturally significant. For most of its history, the courthouse hosted both criminal and civil courts. Beginning in 2010, Polk County began a multi-year project to divide court functions between several buildings. A former department store on an adjacent lot was converted into the Polk County Justice Center, which houses the Polk County Attorney as well as juvenile, traffic, and small claims courts. The former county jail (also on a lot adjacent to the courthouse) was partially demolished and rebuilt to host the criminal courts. After this realignment, the historic courthouse hosts only civil court cases. ==Architecture==