The Hotel de Paris opened on October 9, 1875, modeled after a French inn from Dupuy's native Alencon. At four dollars per night, it charged more than most miners earned in a day, but it delivered something the Mountain West had never seen. Dupuy transformed the former Delmonico Bakery into a European oasis complete with gaslight, radiant heating, and washbasins with hot and cold running water in every room. The arrival of the Colorado Central Railroad in 1877 brought wealthy travelers within reach, and Dupuy's reputation spread. His wine cellar stocked fine wines, champagne, and French liqueurs. The dining room, with its silver maple and black walnut floors and Haviland China imported from Limoges, became the piece de resistance. Railroad speculator Jay Gould dined here. So did photographer William Henry Jackson and English explorer Isabella Bird.

Dupuy was no ordinary innkeeper. He spoke four languages and furnished his study with over 2,500 volumes in French, English, German, and Latin, lending them freely to guests. He acted as chef in addition to hotelier, personally preparing the refined French fare that made his establishment famous. When traveling salesmen passed through Georgetown, Dupuy created three galleries in the hotel where they could display their wares to locals. Through major additions in 1878, 1882, and 1889, he expanded the property to 7,000 square feet. With the final addition, he applied stucco to the facade painted to resemble ashlar masonry, giving his eclectic collection of buildings a unified elegance. The hotel reached its peak in the early 1890s, when Georgetown's silver mines still roared with activity.

The Panic of 1893 devastated Georgetown. The permanent drop in silver prices crushed the mining-dependent economy, and the hotel's fortunes fell with the town's. In January 1892, fire destroyed the McClellan Opera House two buildings away, damaging the Hotel de Paris. Dupuy soldiered on, replacing gaslight with electric lighting in 1893, but the glory days had passed. In October 1900, after a weeks-long battle with pneumonia, Louis Dupuy died. The hotel passed to his housekeeper, Sophie Gally, who died soon after. Sarah Burkholder purchased the property in 1903 and converted it to a boarding house, which she co-managed with her daughter Hazel McAdams. The Georgetown Courier called it "famous the world over" even then, praising the continued excellence of its cuisine.

The Colonial Dames of America purchased the hotel in 1954 after years of declining business, opening it as a museum that same year. Today, the Hotel de Paris contains over 5,000 items from the Victorian era, ninety percent of which are original to Dupuy's time. The silver maple floors still gleam. The Haviland China still rests in its cabinets. Dupuy's personal library remains on its shelves. The building joined the National Register of Historic Places in 1970 and became a National Trust for Historic Preservation site in 2007. In 2014, Colorado Governor John Hickenlooper declared May 24 "Hotel de Paris Day." The 1959 CBS television series Hotel de Paree drew its name from this establishment, and the 1998 film Phantoms, starring Ben Affleck, used the building as a filming location. But the hotel's real story needs no Hollywood embellishment: a man who failed at everything else created something extraordinary in the Colorado mountains.