In 1874, mining magnate Alexander Agassiz, gentleman explorer and part-time oceanographer, had a sprawling summer house built just outside of Newport. It was an ideal setting for a man who'd made strides in the field of marine biology. Set on a small peninsula where the Atlantic meets Narragansett Bay, it was, and still is, a perfect spot from which to observe marine mammals. Long since put into service as a resort, Agassiz’s Victorian mansion has never lost its aristocratic charm. It has nine guest rooms and suites, the most dramatic occupying a mahogany-trimmed turret with a 360-degree view and a soaking tub overlooking the sea. Ten understated wood-shingle cottages—whitewashed wainscoting, apron-front sinks, beach glass–colored fabrics—offer a more low-key alternative just steps from the sand.