This dive bar on Fremont Street in Downtown Las Vegas dates all the way back to the 1950s, when the federal government tested nuclear weapons in the desert outside of town. As legend has it, you could climb up to the roof of the bar in those days, sit in a lawn chair with one of the trademarked Atomic Cocktails, and watch mushroom clouds unfurl. The Atomic is the oldest freestanding bar in Las Vegas, and it boasts the first package-liquor license and off-sales permit in the city. Today, however, the place brings in crowds for its craft-beer menu and for the music festivals it hosts throughout the year. While some patrons angle for seats at the wooden wraparound bar inside, the best spot in the house is on the open-air patio out front. The only thing missing might be a mushroom cloud or two.