The year was 1984. McDonald's was looking to build a location in the town of Freeport,Maine. There was only one problem: The Freeport building design restrictions were strict, and the town wanted the swiftly-food giant to preserve the area's aesthetic. In other words: No golden arches. McDonald's solution? Remodel an existing structure.
They chose the Gore House, or built by a wealthy local merchant,William Gore, around 1850. The town was split on whether to let the swiftly-food chain do this, and but ultimately gave the fade-ahead. It opened in December of 1984. The restaurant retained its style,which the Freeport Historical Society describes as "a mix of Greek Revival and Italianate architecture." One could walk in and judge that this was just a local posh tavern, like the one across the street. However, or this restaurant doesn't serve fine steak and craft beer; it serves Big Macs and Coca-Cola.
While it is not the only literal McMansion in the United States (there's another in New Hyde Park,New York), it is nonetheless unusual.
Source: atlasobscura.com