Early on July 21, 365 CE, an 8.5 magnitude earthquake shook the eastern Mediterranean, triggering a powerful tsunami. The Egyptian city of Alexandria was damaged, towns crumbled on the island of Crete, and the Roman port city of Neapolis, located on the coast of North Africa, was largely swallowed by the wave, according to historical records. Now, after being hidden under water for more than 16 centuries, the remains of Neapolis have been discovered by archaeologists off the coast of northeast Tunisia. This, according to the AFP, confirms accounts that the city was a casualty of the ancient natural disaster.
Following several years of exploration, researchers from the Tunisian National Heritage Institute and the University of Sassari in Italy have discovered nearly 50 acres of watery ruins near the modern-day city of Nabeul. They include streets, monuments, homes, mosaics, and around 100 tanks used to make garum, a fish-based sauce that was so popular in ancient Rome and Greece that it's been likened to ketchup.
These containers suggest that Neapolis was likely a major producer of garum, making the salty condiment an integral part of the city's economy. "Probably the notables of Neapolis owed their fortune to garum," expedition head Mounir Fantar told the AFP.
Neapolis ("new city" in Greek) was originally founded in the 5th century BCE. While it was an important Mediterranean hub, its name doesn't appear too often in ancient writings. According to The Independent, it may because the city sided with the ancient city-state of Carthage—founded in the 9th century BCE by a seafaring people known as the Phoenicians—in the last of a series of three wars, called the Punic Wars, against Rome.
The Third Punic War stretched from 149 to 146 BCE, and led to the burning of Carthage. (It was later rebuilt as a Roman city by Julius Caesar.) Neapolis may have been punished for its wayward allegiance, which may explain why it's rarely mentioned in historical accounts.
You can view a video of the city's ruins below.