The Post House has an historical ambiance that makes it unique from other banquet facilities. Near the turn of the century, the federal government deemed it necessary to obtain land on which to later construct a large federal building for the post office. The lot chosen was on the corner of West Second Street and South Galena Avenue across the avenue from the Lee County Court House and directly next to the the Nachusa House. The construction project commenced in August 1909, while B. F. Shaw was postmaster. It took nineteen months and $90,000 to complete the building. The original building was constructed of Bedford stone, marble, granite, steel and terrazzo. On March 11, 1911, the post office finally opened with thousands of citizens in attendance. When it opened, William L. Frye was the postmaster, as Shaw had died shortly after the groundbreaking. This post office served the postal needs of the Dixon area for 51 years until a new facility was built in 1962.

The building laid empty for two years, then a group of businessmen bought the post office building. They converted the upstairs into a bar and banquet room. These gentlemen were involved in bringing the two grand chandeliers that adorn the main room of the Post House Ballroom. The exact origin of the chandeliers isa mystery, but rumors say they came from the famous Waldorf Hotel in New York City, after it was dismantled.

After changing hands again, the Lee County Council on Aging obtained the building in 1978 with the agreement that if they could maintain the building for ten years they could achieve full ownership. Through city funded grants, the Senior Center was able to renovate the building. The outside of the building, which had been painted gray, was chemically washed to reveal the stone we see today. The three-story spiral stair case was replaced with a two story elevator. The building is handicapped-accessible. Still visible are the markings on the inside windows where the post office boxes were installed. The signs for money orders, general delivery, and savings bonds also remain where they were in the original post office building. The basement of the building was originally used as storage and the furnace area. It is reported that the post office inspectors entered the building through the lower level and used the spiral staircase to reach the thrid floor, where they would surreptitiously watch as the postal workers worked in the main room. The third floor is only accessible, currently, by the rungs on the wall in the closet off of the kitchen.