The metropolis of San Antonio, the seventh-largest city in the United States, encompasses several 18th-century Spanish missions, including the famed Alamo, designated a UNESCO World Heritage site in 2015. While the city boasts several art museums and excellent dining options, the principal tourist destination is the River Walk. Originally a flood-control scheme, this colorful pedestrian promenade meanders through the city for several miles and is lined with vibrant cafés, bars and shops.