Key Marco was an archaeological site (8CR48) consisting of a large shell works island next to Marco Island, Florida. A small pond on Key Marco, now known as the "Court of the Pile Dwellers" (8CR49), was excavated in 1896 by the Smithsonian Institution's Pepper-Hearst Expedition, led by Frank Hamilton Cushing. Cushing recovered more than 1,000 wooden artifacts from the pond, the largest number of wooden artifacts from any prehistoric archaeological site in the eastern United States. These artifacts are described as some of the finest prehistoric Native American art in North America. The Key Marco materials are principally divided between the University of Pennsylvania Museum of Archaeology and Anthropology, University of Pennsylvania; the Department of Anthropology, National Museum of Natural History, Smithsonian Institution; and the Florida Museum of Natural History, University of Florida. The original pond was completely excavated and refilled. It is now covered by a housing subdivision. Excavations of small parts of the site were also conducted in 1965 and 1995.

The Pepper–Hearst expedition of 1895–1897 on the west coast of Florida was sponsored by Dr. William Pepper and philanthropist Phoebe Hearst, and led by the anthropologist Frank Hamilton Cushing. The pre–Columbian finds demonstrate a Shell Age phase of human development and culture.