Over the centuries, the cities became a mecca for various religions. Temples dedicated to Egyptian gods, such as Isis and Osiris, shared the cities with monuments to Greek legends like Hercules. A basilica and two sanctuaries containing the relics of St. John and St. Cyr indicate that the cities still thrived when Christianity swept through the Mediterranean centuries later. Despite the discovery, it's unclear when and why these three cities ended up underwater. But natural catastrophes, like climatic and geophysical changes to the Nile Delta, plus a rise in sea level are the main suspects.
Fish swim through the watery grave of a once mighty metropolis.
Some of the columns and walls in Herakleion looked like they had collapsed - evidence that perhaps an earthquake shook the city into the sea. In any case, archeologists think the cities went under for good sometime in the 7th or 8th century. Divers searching the ruins found coins and jewelry from that era, but nothing from a later time. For the most part, the ruins will not be disturbed. Only a few small pieces and artifacts will be recovered and displayed in museums.