Mexico's Palacio Nacional (National Palace) is full of history, both inside and out. The site itself dates back to the age of the Aztecs, with some of the building materials literally as old as Montezuma. It's a grand building, both in scale and design, and one of the most symbolic structures in the country. Inside, there's even more to captivate a visitor's interest, including the most-visited attraction: Diego Rivera murals. But beyond these enduring works of a Mexican master, there's much more to see, including enchanting courtyards, one of the country's largest and most important libraries, and archives. Guided tours are available by appointment.