How Ancient Trokair Sank

There is a real world city that sank into a limestone cave like Ancient Trokair.

It is called Ubar and it was a city in the Middle East that existed for 5000 years before finally being swallowed whole in 500 or 600 AD. The city prospered as a trade destination (particularly for frankincense, apparently) and its main advantage was the existence of an oasis. Over the centuries, the inhabitants drew up fresh water from a limestone cavern beneath the city. Once it was depleted enough, the cave roof collapsed and the city fell into the earth. It was subsequently buried by sand.

--------

There is another ancient city that was buried three times in a row.

Helike was a Greek city that sank into the earth during an earthquake. The displacement of the city and the earth beneath it caused a huge wave that traveled across the Mediterranean and rebounded back as a tsunami. This tsunami created a lagoon atop the buried city. Over the centuries, river silt deposited atop the city until the lagoon was no more and ground stood in its place.