When Todd County was organized in 1870, Long Prairie residents donated a so-called courthouse. After the roof was repaired, they spent $30 for a heating stove, $10 to paint the inside with lime and mortar and bank the outside with insulating earth, and the building served for three years. In 1873, G.B.V. Williams built a new, two-story frame courthouse 30 by 40 feet at a cost of $2,500. That building was replaced the current courthouse 10 years later.
The Todd County Courthouse is described as avant garde Italian Renaissance. Charles J. Sparks designed it and Samuel Lee oversaw construction of the $20,000 building. The light exterior bricks have been cleaned, and the old windows filled with a white material and lowered in height to the dimensions of modern aluminum combination frames. A blue roof has replaced the original gray.
Built into the hill between double steps ascending the slope of the lawn to the courthouse doorway is an addition of random, uncoursed ashlar granite, which serves as the county museum. Its roof is an extension of the courthouse entry level and holds a war memorial monument and the flagpole. Hewn granite also forms a retaining wall around the main section of the square and was paid for with federal grants.
An addition, known as Annex I, was completed in 1965 at a cost of $200,245. Annex II, the two-story social services building, was added in 1980 at a cost of nearly $2.4 million.