Grotta Palazzese restaurant in Polignano a Mare in Southern Italy was built inside a cave centuries ago, allowing for one of the world’s most unique dining experiences
One is the price. This place is very expensive. You're paying for their uniqueness and the view. They charge €10 per person for cover. They'll charge you €50 for a €10 bottle of regional wine which you can usually find in a local alimentari for around €6, but the rest of the wine list will cost from €100 - €600 a bottle. 
Though most rooms have sea views, ask for one of the seven cave apartments across the road rather than the more boxlike rooms in the main block. 
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