Big Mound Key-Boggess Ridge Archeological District is a prehistoric site on Big Mound Key at the entrance to Charlotte Harbor in Florida. Covering about 13.5 acres, it centers on an unusual shell-earthwork complex of four mounds arranged in a rectangle with ridges and possible canals connecting to the water. Dating evidence places activity as early as about 2,000 years ago, with much material from the Weeden Island period, roughly 400 to 900. Archaeologists interpret it as a village and possibly the seat of a substantial chiefdom that served as an intermediate trade point between peoples around Tampa Bay and the Calusa farther south. Its cultural affiliation remains debated, but it is one of the Gulf coast’s most distinctive mound-and-ridge sites.