It is one of the finest examples of the Greek Revival period in architecture in the Middle West.  The courthouse exists in its original condition, a remarkable preservation, rather than a restoration.  Its interior, which conforms to its exterior, is kept in authentic repair.  The second-floor Circuit Court Room is noted for its beauty.

In 1936, two wings were added across the back of the building, changing it from a rectangle into a T.  The courthouse now contains all the county offices, the health department, and five federal agencies.

The cornerstone of the annex was laid July 31, 1936, in ceremonies arranged by the late Warren G. Hatcher, who for many years was sergeant at arms for the United States Congress in Washington, D.C.  Participating in the ceremony were Arthur Hogg, who drew the plans and supervised the erection of the annex; J.C. Derigo, stonemason contractor; Bud Newhouse, stonemason.  The gavel used in the ceremony had been used in Washington by Champ Clark.

Mortar holding the cornerstone in place was mixed with sand from the Nile River in Egypt, symbolizing the international importance of rural Missouri.  Inside the cornerstone is an Indian hatchet found on the Thomas Butler farm west of New London, representing early history of the county; two petrified snail shells from the old quarry east of town where stone was obtained for the original part of the building; a bronze commemorative medal of the State of Missouri, souvenir of the St. Louis Louisiana Purchase Exposition in 1904, honoring two Ralls Countians, John Owen, who was custodian of the Missouri building at that fair, and Attorney J.O. Allison, one of the Fair Commissioners; a copy of the Ralls County Record of the last week in July, 1936; a card announcing the candidacy of a Ralls Countian, Robert W. Winn, for State Treasurer.  (Winn won the election, one of Ralls County’s contributions to Missouri.)

The annex was so skillfully joined that, on the interior, it is hard for a newcomer to determine where the new part begins.  The upstairs may be reached by three different stairways, and there are several vaults from basement through second story.