The original courthouse built on this site in 1887 included a jail and sheriff's residence. It served a population of about 2,000 people. As a logging town, Aitkin became a railhead and an important stopping point for boats on the Mississippi River. By 1910, the population had grown extensively, making the courthouse facilities inadequate. To free space, a separate jail was constructed in 1915. The two-story, red brick building was designed by Minneapolis architect E.C. Pell. Located immediately west of the courthouse, it included a nine-room sheriff's residence (presently used for office space) and a cell block extending to the rear.
In 1920, Aitkin County established a building fund for a new courthouse, and hired a St. Paul architectural firm, Tolz, King, & Day, to design it. Government officials decided not to issue bonds, delaying construction until 1929. The stone and brick courthouse is a well-preserved example of the Beaux Arts Classicism Style prevalent in the 1920s. Its flat roof is concealed by a parapet. Marble wainscoting, terrazzo floors and oak woodwork grace its interior surfaces, and a stained glass skylight is located in the court chamber. The interiors and exteriors of these buildings retain a significant degree of historical integrity.