Built by John Farnsworth in 1860, this house remained in the Farnsworth family until 1879 when the family moved to Chicago. At that time, Charles Minard, the son of early settler, Ira Minard, bought the mansion. An 1885 fire destroyed the interior of the home, leaving just the stone walls standing. Herbert Nicholson, manager of the St. Charles Condensing Company bought the home in 1891 and restored it.

John Farnsworth, a lawyer from Michigan, came to St. Charles in 1845. During the volatile period leading up to the Civil War, Farnsworth became an ardent abolitionist. One example of his dedication to the cause occurred when abolitionist, Ichabod Codding, came to the Kane County Courthouse to give a series of lectures. Farnsworth and another man patrolled the area outside of the courtroom "with slungshots in their sleeves made of chunks of lead encased in old stockings, ready to give the rioters a warm reception should they attempt to carry out their threats and interrupt Mr. Codding's speeches."

Farnsworth also became involved in politics. Though a Democrat in his early years, Farnsworth left the party and in 1856 was first elected to Congress as a Republican. He was a well respected official, reportedly having many of his speeches published in many newspapers. Farnsworth served as a congressman for 14 years, only abstaining from his political duties during the Civil War when he led the 8th Illinois Cavalry Regiment. In November of 1862, Colonel Farnsworth was promoted to Brigadier-General. He resigned from the service in 1863. Following his resignation, Farnsworth served as a congressman until 1872 when he was defeated by Stephen Hurlbut. In 1879 he moved to Chicago and later to Washington D.C.. He died in 1897.

Soon after the turn of the century the mansion began its new life as a school building. In 1907, the Sisters of St. Dominic purchased the residence and the surrounding property for a private girls' school. The Dominican Sisters remodeled the home to provide classrooms and rooms for boarders. When Mount St. Mary Academy opened on August 15, 1907, it boasted convenient access to both the railways and electric cars, making it easier for students to reach the campus. The expansive Gothic style addition, constructed in 1926, gave the growing and successful school more room to house its classes, which were offered to girls from Kindergarten through twelfth grades. By the 1940s, Mount St. Mary became solely a high school. Day and resident students gained an education in a wide array of subject material including: home economics, typing, math, science, foreign language, and physical education. By the 1970s, the school began to face financial problems, and in June 1972, Mount St. Mary Academy bid adieu to its final graduating class of 110 girls.

It was not long before the old building was once again housing a parochial school. In September 1972, the Lutheran High School Association of Greater Chicago purchased the property. A co-ed high school opened in 1974 and welcomed approximately 300 students. The old Farnsworth mansion housed a thrift shop. The profits of which went to support the school. Like Mount St. Mary Academy, Valley Lutheran High School, or as it was later known, Fox Valley Lutheran Academy, incurred financial problems. By the early 1990s, it was decided that it was best to close the institution. Since that time, the school has again reopened in Elgin, Illinois. (Read more on the St. Charles Public Library website.)