Helike, Greece
Another fascinating site of ancient history called Helike can be found in Greece. This city was submerged after an earthquake caused a massive tsunami, but there was actually a debate between historians about whether this city even existed for quite a time. Eventually, the legend was proven to be true when researchers found artifacts and ruins in 2001. The site had been covered by an inland lagoon for ages before it finally revealed itself. Various dating techniques were used to determine this city went underwater in 373 BC.