Hierapolis

Situated next to Pamukkale, this Roman city (with actual ruins dating
back as far as the 5th century BC) has Roman ruins second to only
Pompei in Italy (ruins I have seen); without the luxury of preservation
under a 10 metre layer of volcanic ash; though Ephesus ranks well too!
See the touristy signs at the entry point (1) - (2) - (3)