A settlement isn’t even close to a city. A settlement isn’t even a village.

Also, you need to read your own article. This is the very first paragraph:

In ancient times, the Adriatic Sea was a major trade route for the Croatian population, which is likely why scientists have discovered various antiquities submerged in this sea. From Roman artifacts to a 2,200-year-old shipwreck and networks of sunken streams, the sea has revealed some fascinating discoveries, reported the University of Bradford. But this time, divers have stumbled upon something that left scientists flabbergasted.

That links to the Bradford article I linked to.