Guadalajara challenges its moniker, Mexico's second city, with a wellspring of the dazzling culture that has put this country on the top of so many international traveler's lists. The brassy fanfare of mariachi music was first played in the region's rural reaches and popularized in Guadalajara's handsome plazas. Before it became a worldwide food trend, birria was a staple in the city's holes-in-the-wall.