Top place to be in Santorini. Not only because it is an archaeological site but also because it gives the most gorgeous view (after the caldera of course!). To get to Ancient Thera, you need a rented car or a taxi and follow the climbing road from Perissa. To my opinion it should be a better organized site with more detailed labels and a museum right next to the site, instead of going to the archaeological museum in Fira to see the exhibits. Greece has the most famous history and the most impressive sites, but it is a pity that no better care is taken of them. Take Akrotiri for example, it's been 5 years since this place closed and it still hasn't open. Let's hope it opens this summer, as announced. Anyway, as for Ancient Thera I can tell you this for sure: you will love the energy of the place and most of all you will adore the view to the beach of Perissa. As breathtaking as Meteora (if you've been there), to make a comparison.