When McHenry County was established in 1836 it extended from the Boone County line all the way to Lake Michigan and the county seat was located in the village of McHenry. A few years later, the Illinois legislature divided the county into present day Lake and McHenry counties. The population of McHenry County was dissatisfied that the County Seat was now so far to one side and in 1842, the legislature passed an act authorizing the people to select a new county seat.

The Act stipulated that the place receiving the most votes must donate 2 acres of land for a public square and build upon that square “as good a courthouse as there is now in McHenry.”

Several locations were offered, including the land claim pre-empted by Alvin Judd which was as close as possible to the geographic center of the county. After an election in September of 1843, Judd’s land was selected as the County Seat, and the following year was platted under the name Centerville.  In September of 1845 the Legislature officially changed the name of the town from Centerville to Woodstock, after Woodstock, Vermont, the hometown of early settler Joel Johnson.

A plain two story courthouse, 33 feet by 40 feet in area, was constructed in 1844. It supposedly stood a little south of the center of the public square. The sheriff’s office, living quarters, and jail were on the first floor, while the courtroom occupied the second floor. The courtroom was used for everything from political meetings to religious services, social occasions and school classes. There was however, no space for county offices.

By the mid 1850’s, the courthouse in the center of the square was proving to be too small, and county officials were renting office spaces in commercial buildings around the square.

The County Board of Supervisors adopted a resolution on June 1, 1855 providing that if the citizens of Woodstock would purchase the property then owned by Mary McMahon, and donate it to McHenry County, the County would donate the old wood-framed courthouse in the square to the citizens of Woodstock. Woodstock citizens did purchase the McMahon property, which was occupied by the Hill Tavern, for $3,000 and the title to the old courthouse and park was transferred to the town.

In May 1855, the Board of Supervisors appointed a committee to procure plans and specifications for a courthouse and jail. The building was to be two stories above the basement, 44 feet square with four end projections, 20 feet by 44 feet, surmounted by a cupola and dome at a cost of $47,000.

The Courthouse was designed by Chicago’s first architect John Mills Van Osdel of Van Osdel and Baumann.  Van Osdel designed many well-known buildings including the Ogden Mansion in 1837, Rush Medical College in 1844, the original Palmer House Hotel, and the old Cook County Courthouse.

The Board of Supervisors seem to have been very involved in the courthouse design, right down to specifying that the “grade of the top of the excavation of the cellar was to be 2 ½ feet below grade on the northeast corner of Jackson Street,” though a newspaper article reported that was not what the plans showed.

Specifications said the brick was to be the best quality of Woodstock brick, hard burnt and that all soft brick deposited at the building might be sent back to the kiln by order of the public building committee, at the expense of the contractors.

In May of 1857, the Committee on Public Buildings reported that the walls of the basement and first story had been completed, that there were 8 to 12 inches of ice and water in the basement, and the walls were badly cracked. During construction the two Woodstock newspapers reported on the controversy regarding the quality/hardness of the brick and the way the stone was cut.

The Board of Supervisors asked Van Osdel and Baumann to look at the situation. The architects felt that the walls were acceptable and a committee was appointed to recommend a plan for drainage.

Another committee was then appointed to look into feasibility and cost of the drainage improvements and also to look into cleansing of the vaults of the privy of the courthouse and jail.

Later that year, the Board of Supervisors authorized the construction of two cisterns to receive water coming from the angles of the roof, both for the accommodation of the courthouse and for the protection of the building in case of fire. The water from those cisterns helped to save the courthouse at least once—in 1871 when fire burned the southwest corner of the square—the same day as the Great Chicago Fire.

The courthouse was completed by February of 1858 and the editor of the newspaper gave his readers a tour of the building, describing the 17 steps to the granite (though it was actually limestone) encased doorway, the interior floor plan, the jail cells and their massive doors.

Nine years after the building was completed, the Woodstock Sentinel reported that the exterior of the courthouse was undergoing a process that involved a thin coat of red plaster or mortar being burned into the face of the brick with muriatic acid and that a white mortar was used to mark fake mortar joint outlines. It was reported that the process cost but little more than painting and looked better and lasted longer. (The results of this effort are still visible today.)

Old Sanborn fire insurance maps show exterior steps on the back side of the courthouse as well as the front, including steps up to the first floor. From descriptions of the interior we know that there was a second curved interior staircase like the one that remains. These features were removed in 1901 to create more office and vault spaces.

For a while the old cells in the basement (or ground floor) were used for the County Clerk’s record storage but they were not fireproof. A 25 feet x 14 feet addition was built on the north side. It provided vaults in the basement and the first floor for the County Clerk and a private chamber on the second floor, off the circuit court room for the circuit judge. (This was around 1904.)

A 45 feet x 18 feet addition was added to the south side of the building in 1905. This included a larger office and better vault room for the Circuit Clerk.

The fence was installed around the courthouse in 1884. This may be when the railing was installed along the limestone stairs.

The most recent Courthouse additions are at the northeast corner and the southwest corner of the building and these were not designed with the same attention to the original appearance.