By calling Kinsterna a castle, we're fudging a bit. It's actually an eco-friendly ancient manor on the outskirts of Monemvasia, an island town in southern Greece. But this fortress-like hillside property is truly regal. Showcasing Byzantine, Ottoman and Venetian architectural influences, the hotel has just 27 designer guest rooms and suites, all of which incorporate original details, such as interlocking domed stone ceilings. The Taverna features its own olive press, and fine dining takes place in the central courtyard in season, with tables arranged on platforms above the ancient cistern that serves as the property's centerpiece. Kinsterna Spa takes full advantage of the hotel's water features, as do the swimming pools, which are fed by natural streams.