The Miami Circle offers more than a gorgeous public waterfront but a prehistoric one that some researchers date back to the Tequesta tribe 1,800 to 2,000 years ago. The 38-foot circle, formed by 24 holes in the oolite limestone, was uncovered in 1999 and recognized as a national historic landmark a decade later. In a city that was founded less than 130 years ago, it's hard to believe people have been gathering on that spit of land where the Miami River meets Biscayne Bay for so much longer. While there are ample spots to take in the blue-green waters of the bay or the enormity of the Brickell and downtown skyscrapers, there's no better fodder to fuel hours-long pondering than to stare into the Circle's captivating circumference.