One of the first settlers of Wise County, Col. Absalom Bishop arrived in 1854. He soon became a leader in the organization of the new country, the election of officials, and the selection of the site of the County Seat.
Bishops group pushed for the top of a bald hill near the center of the county which overlooked the West Cross Timbers and the broad valley of the West Fork of the Trinity River. The hilltop was large enough to accommodate a town square as well as being the highest point in the county. Mr. and Mrs. James Proctor had already deeded sixty acres to the county for the town site. After a bitterly contested counting of the votes, Bishops hilltop won out.

Bishop immediately raised the stars and stripes and revealed his plan for a central commons area surrounded by a square with the business houses facing in and main streets radiating from the four corners. He was elected Wise County's first representative to the state legislature in 1858. Because of his leadership on behalf of Decatur and Wise County, Colonel Absalom Bishop has been called "Father of Decatur".

A public sale of lots was held in 1857 and four lots per block were sold for $100.00 each. The first structure was a sixteen foot square log cabin owned by Joe Henry Martin. Two wooden business houses were soon built. The first to be completed was Electious Halsell's Tavern. Howell and Allen built a two story wooden structure on the south end of the west side. The ground floor was their general store and the Masonic Lodge used the upper story. This store held the town's first post office. Decatur's first physician, Dr. Thomas Stewart, opened an apothecary shop in this building.

Between 1858 and 1861, the Overland Southern Pacific Mail and Stagecoach route, known as the Butterfield Stage Line, passed through Decatur on it's way from St. Louis to California. When on Schedule, the stage arrived at midnight where it deposited mail and occasional passengers at Bishops store.

In 1861, the County built a two story wooden Court House in the center of the square. Lawyers rented office space here. The first photograph gallery and the first newspaper were located here. The building burned in 1881. In 1882, a second Courthouse was built off the Northwest corner of the square. This building burned in 1893.

Wise County has had four Courthouses. The fourth and present structure, completed in 1896 cost $110,000.00 to construct. It was designed by J. Riley Gordon of San Antonio. Said to be architecturally perfect, the building is constructed of pink granit from Burnet County Texas. Each Piece was precut, numbered and shipped close to 200 miles by train to Decatur. The stones were then raised into place using a windlass pulled by donkeys. Amazingly the structure was completed in less than one year.