Extremely worthwhile UNESCO world heritage site atop a massive hill. Take a gondola to to the top and explore around the ruins. It’s a good idea to have a guide with you, as the signage is present but quite technical and the site itself is very imposing. The theatre here is one of the most incredible I have seen(and I’m an archaeologist!). Stop afterwards at the shady and reasonably-priced café for a cold drink before you take the gondola back down. Tons and tons of photo ops… Even if you’re going to a bunch of classical sites in Turkey, this one should be on your list!