English: Residence of United States Senator (R-NV) William Morris Stewart located in the Dupont Circle (then known as Pacific Circle) neighborhood of Washington, D.C.

"Stewart's Castle" was designed by Adolf Cluss in 1873 and became one of the first houses constructed in the neighborhood. The home was nicknamed "Stewart's Castle" because of its size, design, and the fact only a few small homes had been built in the neighborhood up until then. After construction of Stewart's Castle was completed, wealthy residents began moving to the neighborhood and building large mansions around the Circle.

From 1886 to 1893, the building was used as a legation by the Chinese government. In 1901, less than 30 years after its construction, the building was demolished. The property sat vacant until 1923 when a Riggs Bank branch was constructed on the site. That building still stands and is now home to a PNC Bank branch.