The Harris-Cameron Mansion was home to the city's founder, John Harris, Jr. and his sons from 1766 to 1835.

Between 1853 and 1861, it was owned by the Rev. Beverly Waugh who, with his wife, opened the Pennsylvania Female College in the mansion.

In 1863, the house was bought by U.S. Senator Simon Cameron, who later became Abraham Lincoln's first Secretary of War and Ambassador to Russia. Cameron set about turning the Georgian house into a Victorian mansion in the Italianate style. It is this house that visitors see today, along with some later additions.

Among the outstanding features is a grand parlor with double fireplaces, crystal chandeliers, and mirrors brought back from Europe by Cameron. Seen elsewhere in the house are a tall case clock and chairs belonging to Harris, personal items used by Cameron, and a high-style Art Deco bathroom and secret liquor cabinet added by later owners. The house became the headquarters of the Historical Society of Dauphin County in 1941.

The mission of the Historical Society of Dauphin County is to collect, preserve, exhibit, publish, and promote interest in the history of Dauphin County for the education, enjoyment, and benefit of the public.

Constructed c. 1766 by John Harris, Jr., son of the pioneer frontier trader and ferry operator John Harris, the John Harris-Simon Cameron Mansion was occupied in the second half of the 19th century by Simon Cameron, entrepreneur, banker, U.S. Senator, Lincoln's first Secretary of War and later Minister to Russia.

Harris, Sr., an English brewer, was an associate of the Penn family and received a land grant as an inducement to come here. The Penns wanted Harris to establish good relations with the local natives and to facilitate the settlement of the central and western portions of the Penn's colony. John Harris, Jr. was born at Harris Ferry in 1727, and after his father's death in 1748, Harris continued in his father's occupations and found favor with local Native Americans as "an honest man very well-known to our Nation, as was his father before him." Harris and his associates were responsible for laying out in 1785 what was to become present-day Harrisburg.

Built of local grey limestone, the house was constructed in a simple Georgian-style plan of four rooms downstairs and four upstairs. This original layout was altered sometime in the first half of the 19th century by his sons or subsequent owners with the addition of a large new dining room and kitchen and bedrooms. When Simon Cameron bought the house in 1863, he transformed it into a Victorian-style showplace and furnished it with furniture, mantles, stained glass and mirrors purchased in France, Italy, and Bavaria while in route to Russia.

The house was home to several notable Harrisburg citizens. Harris, Jr.'s sons David and Robert lived there until 1835, when Robert sold it to Thomas Elder, a prominent lawyer, state Attorney General, organizer of the Harrisburg Bridge Company, and president of the Harrisburg Bank.

Upon Elder's death in 1853, the house was sold to the Rev. Beverly Waugh, who with his wife Sarah turned the house into the Pennsylvania Female College, a school for young ladies. Perhaps because of the social turmoil of the beginning of the Civil War and the death of the Rev. Waugh, the school closed in 1861.

Simon Cameron, a member of the board of directors of the school, purchased the building in 1863. Cameron was born into a poor family in Lancaster County in 1799. Through hard work, shrewd investments, and some said, unethical business practices, he had accumulated a considerable fortune by 1862.

After finalizing the purchase of the house, Cameron set out to convert it to a grand Victorian mansion. He created a large parlor from two smaller rooms and added an alcove for more light, a solarium, walkway, butler's pantry, and grand staircase. He also had the floors in the front section of the house lowered three feet into the basement because the 11-foot ceilings in the parlor could not accommodate his new 14-foot mirrors. Cameron divided his time between the mansion and his home in Donegal, Lancaster County, until his death in 1889.

The house passed to Cameron's daughter, Margaretta, widow of Richard Haldeman, a local newspaper publisher and Congressman. With her passing in 1915, the house was inherited by her son, Richard, who was president of the Harrisburg Bridge Company. Haldeman redecorated, modernized, and made the last addition to the house, the West Alcove, with its spectacular Art Deco bathroom. He was the last of the Cameron family to live at the mansion, dying in 1933. His sister Elizabeth Wright donated the house and other family items to the Historical Society in 1941.

The mansion, located on Harrisburg's riverfront at 219 South Front Street, stands today much as it did in Cameron's day. It is furnished with pieces from both the Harris and Cameron families, as well as furniture, books and decorative items from Dauphin County collected and donated over the intervening years. While administering the Harris-Cameron Mansion, the Historical Society of Dauphin County also maintains an archives of historic documents and a research library open to the public.

The exterior of the mansion has recently undergone a major restoration, the first in nearly 30 years. Plans during the 2016 anniversary year include work in establishing an appropriate landscape plan for the gardens, restoration of garden walls, iron fences and gates, and restoration work on the interior, including the 19th century French wallpaper in Cameron's solarium.