Downtown Tucson's culinary identity crystallized in 1880 when the Southern Pacific Railroad carried Mexican cattle ranchers, Chinese laborers, and Anglo merchants into a single streetgrid. Their competing kitchens—mesquite-grilled carne asada, Sonoran wheat tortillas, and later the Tohono O'odham tepary bean—collided into a regional cuisine UNESCO recognized as the United States' first City of Gastronomy in 2015. The designation honored four thousand years of continuous agricultural cultivation in the Santa Cruz River basin, a depth of food memory unmatched north of the Mexican border. Today that heritage unfolds along a compact half-mile corridor between the Historic Depot and the Presidio San Agustín del Tucson, where nineteenth-century adobe mercantiles now shelter third-generation taquerías and James Beard-nominated chefs. The Sun Link streetcar, operational since 2014, threads through the district on a 3.9-mile loop, connecting tasting stops that would otherwise require midday heat exposure. A Tucson walking food tour typically pairs six sit-down tastings with architectural commentary—guides point out the 1929 Rialto Theatre's Spanish Colonial Revival facade while explaining how Barrio Viejo residents preserved mesquite-roasted chiles through territorial Arizona's hottest summers. The district's compact scale rewards pedestrian exploration. Most culinary walks cover fewer than two miles, yet traverse three distinct micro-neighborhoods: the Warehouse Arts District's adaptive-reuse breweries, the Mercado San Agustín's artisan food hall, and the original Barrio Histórico's family-run loncheras. Guides frequently pause at El Charro Café, credited with inventing the chimichanga in 1922, and at the wildflower-planted median of Stone Avenue, where desert botanicals—prickly pear, cholla buds, mesquite pods—illustrate indigenous foodways still practiced in Tucson's modern kitchens. The tours operate year-round, though October through April offers temperate conditions for leisurely tasting.