Roman ruins on the coastline of the Bay of Naples at Pozzuli. At one time they were considered by antiquarians to have originally been a temple: modern archaeology says a market.
An example of bradyeseism, slow motion seismic activity. At some stage oveer the past two millennia, these ruins were underwater for a long time, not because the sea level rose, but because the ground level was lowered.
Subsequently ground level rose again. The structure is now once again on (almost) dry land. But some of the stone shows its submerged history thorough the deep pitting which was caused by marine molluscs.