Göbekli Tepe ~ This recent discovery doubled the known history of humankind. This site is over years old, 7000 years older than Stonehenge & the Egyptian pyramids. So far, they have uncovered and excavated only of the ruins in the last 13 years.
The Lost City of Heracleion: Lost Egyptian City Revealed After Years Under Sea. The ruins of the lost city were found 30 feet under the surface of the Mediterranean Sea in Aboukir Bay, near Alexandria.