Ancient structure twice the size of Stonehenge found submerged . Score: 7 Archeologists believe it was built on land then later submerged . Guesses as to site 's purpose ; could be ceremonial structure or huge ramp .
Ancient structure twice the size of Stonehenge found submerged . Thought to be between 2,000 and 12,000 years old . Archeologists believe it was built on land then later submerged . Guesses as to site 's purpose ; could be ceremonial structure or huge ramp .