The first courthouse of Johnson County was erected in Napoleon, Iowa in the year 1838. A short time later the county seat moved to Iowa City. A jail and temporary courthouse were completed there in 1842. The courthouse was 56 by 28 feet, two stories high, and made of brick.
A second courthouse was built, but the records are unclear as to specifications. By 1897 cracks in the walls of this courthouse were endangering valuable records.
In 1899, construction began on the present courthouse. The cathedral-like building is an example of Romanesque Revival architecture. There are impressive stone carvings above the entrance. It cost approximately $111,000 to build.