There are "Atlantic Hotel" signs painted on both sides of the old Atlantic Hotel. According to the National Register of Historic Places these signs are original. If such is the case they must have been painted with very good quality paint, as they would be a century or more of age.
Atlantic Hotel
The construction of the Milwaukee Road and the reconstruction of the Northern Pacific Railroad through Missoula sparked a second railroad-era building boom in the early twentieth century. The need for accommodations for both railroad workers and passengers occasioned the construction of several hotels at the city’s north end near the depot.
The Atlantic Hotel was one such establishment, designed by Missoula’s most celebrated turn-of-the-twentieth-century architect, A. J. Gibson. Completed in 1902, the ground floor included a barber shop, saloon, and restaurant with the “best meals in the city.” Patrons could secure lodging on the two upper floors for seventy-five cents and up. Commercial façades often received more architectural attention than a building’s sides and back, and these differences often reveal stylistic changes. The hotel’s façade reflects twentieth-century tastes with its fine high-fire polychrome brick detailing, flat window heads, and elaborate molded metal cornice. The rest of the building exhibits more traditional construction of low-fire bricks and arched window design carried over from the previous century. Original signs adorning its side further enhance the historic charm of this well-preserved, turn-of-the-twentieth-century landmark.
From the NRHP Plaque