The inn's architect was 29-year-old Robert Reamer, an architect for the Yellowstone Park Company, which was affiliated with the Great Northern Railway. Reamer was hired by Harry W. Child, the president of the Yellowstone Park Company, who had met Reamer in San Diego through mutual acquaintances.
With its spectacular log and limb lobby and massive (500-ton, 85-foot) stone fireplace, the inn is a prime example of the "Golden Age" of rustic resort architecture, a style which is also known as National Park Service Rustic. It is also unique in that it is one of the few log hotels still standing in the United States.
Initial construction was carried out over the winter of 1903-1904, largely using locally-obtained materials including lodgepole pine (the bark was later removed in 1940) and rhyolite stone. When the Old Faithful Inn first opened in the spring of 1904, it boasted electric lights and steam heat.
The structure is the largest log hotel in the world; possibly even the largest log building in the world. In 2007 the American Institute of Architects conducted a survey to determine the 150 favorite buildings in America; the Old Faithful Inn ranked 36. The Inn, which was designated a National Historic Landmark in 1987, is itself part of the Old Faithful Historic District.