A place worth visiting. It is located on the embankment in Side, free to visit. The view is impressive: something ancient plus a delightful sea, next to a bay with modern ships and boats. There are streets with shops and cafes nearby, everything looks very European.
There is also a museum part with the rest of the ruins nearby, admission for September 2024 is 17 euros per person, but payment is only in local lira (the cost in lira is not indicated, probably due to rampant inflation). Whether it makes sense to pay this amount is up to everyone to decide. It's probably more economical as part of the tour.
All the cafes in this place are very unusual, the food is delicious, but the price is not cheap (3 salads and 3 non-alcoholic cocktails - 10,000 rubles). Almost all the sights are behind the fence, far away. Admission is 17 euros per person (approximately 9,000 rubles for a family of 4 people, this is for admission). I do not recommend going on an excursion here, perhaps it would be different with an interesting guide...