The Andrew Johnston House, located in the town of Pearisburg in Giles County, boasts a beautiful five-bay façade, Flemish-bond brickwork, and molded brick cornice. Built in 1829, it is the oldest surviving house in Giles County and is a classic example of western Virginia Federal vernacular architecture. Andrew Johnston, along with his brother David, was one of the founding settlers of Giles County, and in 1806, they contracted to lay out the town lots of Pearisburg, which is now the county seat. Upon the death of his mother in 1853, Andrew Johnston's son, Harvey G. Johnston, inherited the property, and he used it as his residence and medical practice. As a prominent physician in the county, Dr. Johnston ran his practice from a small wooden building on the grounds, which was later continued by his son, Harvey G. Johnston, Jr. In 1995, the Andrew Johnston House was deeded to the Giles County Historical Society to serve as a museum that honors the Johnston family and their contributions to the county's history.

The interior design is based on a simple colonial plan with a central hall flanked by a room on either side. A dining room ell wing is attached at the rear on the ground floor. The parlor and upstairs bedrooms still have their original wide-plank yellow pine flooring, and the house possesses numerous pieces of Johnston family furniture. Rare and unusual decorative painted borders can be seen in the principal rooms on both floors.

In 1857, Dr. Harvey Green Johnston, Colonel Johnston's son, expanded the house with a wooden addition attached to the rear dining room wing. It replaced the original kitchen, which was located in the cellar. The Johnston family continued to renovate and update the house over the years. The current pressed-metal shingle roof dates from circa 1900, and the house was the first in Pearisburg to install electricity and telephones.

In 1993, the Andrew Johnston House was added to the Virginia Landmarks Register and the National Register of Historic Places.

Restored in 1998 to its nineteenth-century appearance, the Andrew Johnston House is an excellent example of a prosperous middle-class dwelling in the rural antebellum South.