From 1856 to 1874 the original courthouse of Adair County was located in Fontanelle. This small, two-story building was made of locally harvested woods. After the county seat moved to the village of Greenfield in 1874, the first courthouse was used as a school, church, meeting hall, and town hall until it burned down in 1910.
In the meantime, a second two-story courthouse was built in the town square of Greenfield for $8,000. This building suffered the same fate as the first courthouse when it was destroyed by fire in 1889. An opera house served as the courthouse until the third courthouse could be completed in 1892.
The cornerstone of the present courthouse was laid on July 4, 1891. Some of the historical items placed inside the cornerstone include a bible, bottles of wine, corn, and oil, as well as the history of Greenfield and a letter to be opened by the oldest man present when removed. This building serves as the courthouse today. It is constructed of brick and cost $26,768, including furniture.