OT/ Mystery map of yesteryear.

Always remember reading about the Piri Reis map. Still find this fascinating that we could have lost so much knowledge from years ago.
This map was created in 1513 by the Turkish Admiral and Cartographer named Piri Reis. It still bamboozles scientists today and so most historians file it under "Outlier" which is lazy and ignorant. It's most famous for having what appears to to be the coast line of Antarctica.
Antarctica was Discovered around 1820.
In fact for many years it was thought that Irishman Edward Bransfield on a British expedition was the first person to sight the Antarctic continent (rather than offshore islands) on the 30th of January 1820 with the ship Williams. The previous year the same ship under the command of captain William Smith had discovered the South Shetland Islands while on a commercial voyage. When Smith reported what he had found on returning to Valparaiso, Chile, Captain Shirreff of the British Royal Navy chartered the ship and appointed Bransfield as captain to return south the following season and investigate the area further.
(from cool Antarctic website)

At the last ice age ending the sea levels would have been so much lower then today. In fact a fair reason why a lot of earlier built up areas are not visible is because most would have been inundated by the deluge of melting snow/ice.
Just like today, many cities are built for harbors and water ways ans so are build by the sea.
But would we know we were here after another flood?
Our ancestors knew a lot more then we realize.

Changing sea levels probably account for the truths behind several "mythical" lost towns and villages around our own coastline as well as others, including Atlantis. BBC currently have a story on similarly lost islands off the coast of Wales which appear on a medieval map