The Dungeness ruins sit at the southern tip of Cumberland Island, a short walk north from the ferry dock. The Carnegie family built their main mansion here in 1884 — a 59-room Queen Anne structure that served as the family's winter retreat. It burned in 1959, and what remains are the brick walls, chimneys, and the formal garden that once surrounded it, now half-consumed by subtropical vegetation.
The atmosphere is genuinely memorable. Spanish moss hangs from the live oaks that have grown up through the old garden terraces. Wild horses graze in the formal grounds. The ruins of a swimming pool, a stable block, and various outbuildings are scattered nearby. The site is always open to day visitors who make the ferry crossing. Allow an hour to explore the ruins and the adjacent beach.