John David Mongin was a wealthy Sea Island cotton planter at Haig Point plantation on Daufuskie Island who made several investments after moving to Savannah. Mongin purchased the empty half trust lot directly across from the present site in August 1797 and built this two-and-a-half-story, five-bay, central-passage clapboard house. Mills B. Lane Jr., who carried on the leadership of C&S Bank established by his father, had the Mongin House moved across the square when plans were made to build the parking garage. The landscape construction plan, which included the rear yard and surrounding sidewalks, was designed by local landscape architect Clermont Lee in 1966 and revised in 1967. The new basement is lower than the previous one and the porch is not original. On the trust lot to the north, the smaller Spencer-Woodbridge House (c. 1795; c. 1830, c. 1960 additions; 22 Habersham Street) is similar in appearance, remains on its original site, and has a rare, though likely modern, side garden.