Chateau-sur-Mer was completed in 1852 as an Italianate villa for William Shepard Wetmore, a merchant in the China trade, who was born on January 26, 1801, in St. Albans, Vermont. The architect and builder was Seth C. Bradford; the structure is a landmark of Victorian architecture, furniture, wallpapers, ceramics and stenciling. Mr. Wetmore died on June 16, 1862, at Chateau-sur-Mer, leaving the bulk of his fortune to his son, George Peabody Wetmore. George later married Edith Keteltas in 1869. During the 1870s, the Wetmores departed on an extended trip to Europe, leaving architect Richard Morris Hunt to remodel and redecorate the house in the French Second Empire style.
As a result, Chateau-sur-Mer displays most of the major design trends of the last half of the 19th century. The house is constructed of Fall River Granite.Hunt’s alterations greatly expanded the house, adding a new three-story wing, a porte-cochere, and a projecting four-story tower with mansard roof. The carriage house was also enlarged, in a manner sympathetic to Bradford’s original design. Hunt also designed the entrance gate of the estate, which is somewhat Greek Revival in style, but with posts modeled after Egyptian obelisks.
The centerpiece of the mansion’s interior is its Great Hall, a massive three-story chamber with a 45-foot (14 m) ceiling and broad balconies. The Billiard Room is in the Eastlake style, with oak timbers aligned diagonally on the ceiling, and herringbone flooring. The Library has an Italianate design, and was actually designed and built in Italy, then disassembled and transported to Newport. The Marble Hallway originally served as the house’s main entrance, and is finished with a variety of different marble colors. It was closed off in 1920 by replacing the main door with a bay window. The Green Room served as a ladies’ reception area, and was designed in 1900 by Ogden Codman, Jr. in the Louis XV style. The Ballroom, decorated with crystal chandeliers and fine plaster decoration, is one of the few rooms that remained relatively unaltered by Hunt’s work. The Dining Room is, like the Library, in Renaissance Revival style, and was also built in Italy.
Unlike most of the “cottages” built in Newport during this period, Chateau-sur-Mer was one of the few built as a year-round residence. This was because the Wetmores were a New England family who made Newport their home. George was very active in Rhode Island politics during the late 19th century. A lifelong Republican, Wetmore was a member of the Electoral College of 1880 and again in 1884. In 1885 Wetmore was elected Governor of Rhode Island, and went on to win re-election in 1886, but was defeated in an attempt for a third term in 1887. In 1894, the Rhode Island General Assembly elected Wetmore to the United States Senate, where Wetmore remained until 1913. In the Senate, Wetmore served on the Naval Affairs Committee and the Appropriations Committee.
The house was added to the National Register of Historic Places in 1968 and purchased by the Preservation Society of Newport County in 1969. It was declared a National Historic Landmark in 2006.The former carriage house and stables for the Chateau-Sur-Mer estate are owned by Salve Regina University and are currently being renovated as a center for visual art and cultural and historic preservation known as Wetmore Hall.