Inheriting an estimated $80 million and a Gilded Age cottage overlooking the Atlantic in Newport, R.I., is daunting at any age. Doris Duke did so when she was just 12 years old. She used that fortune wisely, becoming an ardent preservationist and a knowledgeable collector of art and antiques that she acquired from all over the world. Her artistic vision is expressed in the exhibition The Duke Treasure Houses (401.849.7300, www.newportrestoration.com), open through November 6 at Rough Point, Duke’s 49-room estate. The collectibles include Ferdinand Bol’s 17th-century portrait Lady in Pearls, an 18th-century Russian ivory and silver table, and Brussels tapestries dating to 1510. More whimsical are a life-size silver swan by Tiffany and a silver mounted saddle. But the most exceptional display is the one found outside: the expansive grounds that lead down to the breaking sea.