This palatial property, officially opening at the end of the year, has a lot to recommend it: a renovated 18th-century castle, a private beach and views of the Bay of Naples and Mount Vesuvius. Inside, there’s a salone with Pompeian-style frescoes and luxurious antique-filled bedrooms; outside, a garden with a terrace overlooking the sea. Doubles from $270; Via Posillipo 222; 011-39-081-2483-032.