Most people are likely familiar with the ancient city of Pompeii that was buried by a series of eruptions of Mt. Vesuvius (near modern-day Naples, Italy) in 79 AD. Less commonly known is Herculaneum, another nearby city buried by the same eruptions.
The Temple of Poseidon (foreground) and Temple of Hera (background) in the too-seldom-visited site of Paestum, Italy.
Paestum is in Italy, and was once a Roman city, but it started out as the Greek colony of Poseidonia. The Temple of Poseidon (built around 460-450 BC) is the largest and best-preserved of Paestum’s temples. But in actually, nobody knows for sure which god / goddess it was originally dedicated to; given the city’s original name, it may well have been dedicated to the city’s namesake — but maybe not.