Rosario, Historic site in San Juan County, United States.

Rosario is the former estate of Seattle mayor and shipbuilder Robert Moran on Orcas Island, built between 1906 and 1909 with wood and stone quarried on the island. Its five-story Arts & Crafts mansion faces the Rosario Strait and holds a music room with a 1913 two-story Aeolian organ of 34 ranks and over 1,900 pipes, plus a 1900 Steinway grand piano. Stained glass windows, a Tiffany chandelier and two libraries fill the house, set in 84 acres of paths and water features.

Robert Moran, a former Seattle mayor and shipbuilder, moved to Orcas Island for his health and built the estate between 1906 and 1909 using wood and stone found on the island. In 1921 he gave a large part of the property to Washington State for Moran State Park; he sold the resort in 1938. It opened as the Rosario Resort and Spa in 1960 and was listed on the National Register of Historic Places in 1978.

The estate takes its name from the Rosario Strait it overlooks. Its music room holds a 1913 two-story 34-rank German-style Aeolian organ with over 1,900 pipes and a 1900 Steinway grand piano, and the mansion keeps a museum of Robert Moran with original furnishings.

The resort sits on 84 acres of grounds laid out with paths and water features, and the marina and grounds stayed open even while the hotel was closed in 2024. The mansion holds a museum on Robert Moran with original furnishings, and the music room keeps a 1913 Aeolian organ of over 1,900 pipes and a 1900 Steinway grand. The site lies on Orcas Island in the San Juan archipelago, within San Juan County.

The mansion's music room holds a 1913 two-story Aeolian organ with 34 ranks and over 1,900 pipes, plus a 1900 Steinway grand piano. Both were part of Moran's original furnishings, and the mansion now serves as a museum honoring him.