The Unitarian Church, a National Historic Landmark, is the oldest Unitarian church in the South. In colonial Charleston, members of the Circular Congregational Church (then known as the Independent Church) were so numerous the need arose to build a second church building. Construction began at this Archdale site in 1772, but was temporarily interrupted by the Revolutionary War. The small rectangular brick church was finally completed in 1787. In 1817, the Archdale congregation was chartered as the Second Independent Church, with a Unitarian minister presiding. As the American Unitarian Association was not organized until 1825, it was not until 1839 that this congregation was rechartered as Unitarian. The church received a major remodeling in the mid-19th century and is today a statement of the emotional mood of the era when the romantic and picturesque were dominant not only in literature but also in building design.
Architect Francis D. Lee is responsible for the 19th-century Gothic Revival additions to the building.In 1852 his two-year renovation of the church began, which included the addition of the rear chancel, a four-story tower and stucco to the original brick walls. The remodeled church exhibited typical Gothic features such as the crenellated tower, arched windows, stained glass panels, and Tudor arch entrance. On the exterior, false buttresses are used for visual effect rather than as structural supports, as is the interior vaulting, made of lath and plaster. This vaulting is modeled on the that of Henry VII chapel at Westminster in London, England. When the building suffered significant damage in the earthquake of 1886, people across the country sent donations to fund repairs.