This is the third Mason County Courthouse, designed by Dallas architect E. C. Hosford and built in 1909-1910, currently celebrating its 100th anniversary. It is Classical Revival style and cost $39,786, according to county records. The elaborate metal cornices projecting above the eaves were constructed by the Lange family, who moved to Mason from Brenham after finishing this project. During the 1980s the exterior of the courthouse was repainted using original colors. Most rooms have a fireplace trimmed with ornately-pressed metal. The district courtroom was renovated with a grant from the Texas Historical Commission in 1986. Originally the courthouse lawn was packed dirt with mesquite trees.

The stately pecan trees of today were planted during the 1930s. The fine stonewall surrounding the courthouse lawn was built by local contractors Henrich and Ischar in 1927-28. Mason County is currently moving forward with possible plans to participate in the Texas Historical Commission's Courthouse Restoration program. If selected, the county's beautiful landmark will soon be getting a facelift, possibly as early as 2012. The other two buildings on the grounds were built in the 1940s under the Works Progress Administration (WPA). In June 1938 the firehouse burned with all firefighting equipment and trucks. The town raised $1,237 for new firefighting equipment the next day after the fire. In September, Commissioners Court started plans for a new fire station with the aid of a WPA loan.

The stone in the structure was obtained from the old Koocksville Mill, northwest of town. The other rock building was constructed of native stone and brick and now serves as public restrooms. Today the old firehouse houses Mason Law Enforcement Center.