The Boulder Dam Hotel is a 1933 Dutch Colonial Revival hotel right on the historic district's main street. It functioned as the high-end accommodation for dam visitors throughout the 1930s and 40s, and was substantially restored in the 1990s after years of decline. It is still a working hotel with around 20 rooms — comfortable rather than luxurious, with original tile work and a wide front porch.
Even if you are not staying, the lobby and the small Hoover Dam Museum upstairs are worth a look. The museum (entry is by donation) is run by volunteers and covers the construction of the dam with original photographs, tools, and oral histories from workers' families. The restaurant downstairs serves a simple American menu and is the most atmospheric place to eat in town.