This residence was built in the Shaker style in 1837. Its owner, Leonard Howard, a contractor and builder, was also proprietor of the Howard House Hotel. His wife, Caroline, was a member of the spiritualist movement and believed that the spirits of the dead could send and receive messages through her and others who knew how to contact them.

It is said that Mrs. Howard played a role in the infamous Richard's Riot of 1849. Her psychic powers reportedly enabled her to reveal the location of the body of a recently deceased young bride named Mrs. Kenyon, which had been robbed by a Franklin Medical College student.
Caroline Howard and her daughters held many séances in the house, and the services that Mrs. Howard offered became quite popular with grieving wives during the Civil War. Mrs. Mary Todd Lincoln, who had suffered the loss of her husband and two of her sons, came to St. Charles in 1871. It is said that she consulted with Mrs. Howard daily while she stayed at the Howard House Hotel under the alias of "Mrs. May."

After Caroline Howard died, one of her daughters continued conducting the séances in the home. Eventually she married C.L. Blanchard, who was an undertaker. For a short time, the house served as a funeral parlor. One of the downstairs rooms was used as an embalming and viewing room until Mr. Blanchard relocated the business to a building on Main Street. The front door of the house still has the name "C.L. Blanchard" etched into the glass.

The Leonard Howard House served as a residence for three generations of the Howard family. After the last of the family passed away, the home was sold and renovations began. During the renovations, several discoveries were made. Two antique parasols, one of which now resides in the St. Charles History Museum, were discovered in the house. A book dating from 1834, which had been hidden between two walls, was also found. At an estate sale held in the 1990s, a shawl belonging to Mary Todd Lincoln was auctioned, along with several other important antiques and artifacts from the house.

The house has been restored and it remains one of the most historic houses in St. Charles.