The pin measures about 2-1/4'' x 13/16''. It appears to be in mint condition as pictured.
Below here, for reference is some additional information about The Historic Charleston Foundation:
Historic Charleston Foundation
From Wikipedia, the free encyclopedia
The Historic Charleston Foundation (HCF) was founded in 1947 to preserve and protect the integrity of architectural, historical and cultural heritage of Charleston, South Carolina, U.S.A.. The Foundation undertakes advocacy, participation in community planning, educational and volunteer programs, the preservation of properties, research, and technical and financial assistance programs.
History
Established in 1947, Historic Charleston Foundation (HCF) is a nonprofit organization whose mission is to preserve and protect the historical, architectural and material culture that make up Charleston's heritage. The Foundation is known for its education and outreach, preservation and advocacy programs including protective covenants and easements.