Discovered in 1998, the "Brickell Point Site" was listed on the National Register of Historic Places in 2002 and the "Miami Circle" in 2007. Miami Circle at Brickell Point is a National Historic Landmark (2009) and archaeological site, which is located at the mouth of the Miami River in downtown Miami, Florida.
In 1998, archaeologist Dr. Robert S. Carr, who was at that time, the Director of Miami-Dade's Historic Preservation Division, conducted a basic excavation prior to a downtown riverside construction of two high-rise buildings. Old low-rise apartments from the 1950s had recently been demolished to make room for the new construction. During this salvage exploration, intact black earth midden deposits were discovered at the site. Carr's team, which included county archaeologist John Ricisak serving as the field director, and field crew provided by the Archaeological and Historical Conservancy, Inc., uncovered Glades culture and Tequesta artifacts of shell, stone, bone, and pottery. Excavation within three areas at the Brickell Point property revealed additional black earth middens, and numerous artifact-filled holes in the Miami oolite limestone.
On examining the layout of the holes and adjacent larger oval and rounded rectangular basins, the project's surveyor, Ted Riggs, postulated that they were part of a circle 38 feet in diameter. Having calculated the center, he projected the likely location of the remaining holes. Excavation revealed that there were 24 holes forming a perfect circle in the limestone. In January 1999, the discovery of the "Miami Circle" was announced. Carr said the Miami Circle “may be of national significance as it is believed to be the only cut-in-rock prehistoric structural footprint ever found in eastern North America.”
An independent assessment of the site's origin and significance was conducted in May 1999 by archaeologist Brent Weisman (Univ. of South Florida), archaeologist George Luer, and preservation architect Herschel Shepard (Univ. of Florida). They concluded that the site probably represents the footprint of an important structure, built by the Tequesta or their ancestors. In order to date the site, pieces of charcoal were radiocarbon dated. The results indicated that the wood was between 1,800–2,000 years old. However, some scholars doubted that the circle is as old as the wood, so further evidence to support the theory that the holes were of that age needed to come to light. That same year, Tom Scott and Harvey Means of the Florida Geological Survey, conducted a thorough survey and confirmed the approximate dating by studying the buildup of a calcite duricrust on the edge of the cut faces of the postholes and larger basins. Though this is an imprecise way to date the construction of the circle, the two experts ruled out that the holes were of modern origin.
Due to a frenzy of media attention and public interest in the archaeological discovery, the City of Miami and the State of Florida heard public appeals for preservation of the site by purchasing it from the developer. By September 1999, Miami-Dade County and the developer reached a settlement agreement, concluding that the County would pay 26.7 million dollars for the property. Florida Governor Jeb Bush and Cabinet agreed to contribute state funds to the acquisition, pending an archaeological investigation by the Bureau of Archaeological Research (BAR). Assessment of the property by BAR concluded that the Miami Circle is ancient and of human origin. Intact deposits were found across 70% of the 2.2 acre property, including many other holes cut into the limestone not associated with the circular structure. A waterfront park managed by HistoryMiami opened in 2011. The circle itself remains buried to protect it, while an audio tour and several panels describing it are available to the public.
page information credit: Florida Division of Historical Resources, Palm Beach County, Miami-Dade County, Wikipedia, HistoryMiami, Archaeological and Historical Conservancy, The Florida Anthropologist, Miami Herald
photos from the sources listed above, as well as publicly posted online sites with thanks to the contributors