Coral Castle sits in Homestead, Florida, a compound of carved coral stone weighing an estimated 1,100 tons in total, with individual blocks reaching 30 tons. This episode of the classic "In Search Of" series lays out the puzzle at its center: the castle was built almost entirely by one man, Edward Leedskalnin, a slight, reclusive Latvian immigrant who worked alone, mostly at night, and never let anyone watch him move the stone. No machinery was ever found on site to explain how he quarried, shaped, and positioned pieces that size. Leedskalnin himself claimed to have rediscovered the lost building methods of the Egyptians and the builders of Atlantis, a claim the film neither fully credits nor dismisses outright. The episode surveys the physical evidence, the gap in the historical record, and the theories, magnetism, leverage, forgotten mechanical tricks, that have tried to close it, leaving Leedskalnin's actual method as unresolved as it was the day he died.