You think your local big box supermarket is big? Imagine having to take a taxi from one section to another.

La Central de Abasto is the largest wholesale market in the world. It covers 327 hectares (808 acres) and serves as the central axis for Mexico's food supply. Or at least it did when it was built. Once 80% of the country's food passed through this market; today it's more like 20% thanks to competition from Costco and Walmart. However, the market has adapted by allowing retail sales alongside the wholesaling, which means you're now free to explore and shop to your heart's content. Arrange car service and a tour guide through the concierge at the Sheraton Maria Isabel, and plan to get up early for this overwhelming experience. Don't forget your camera.

If that sounds too crazy, the Mercado de la Merced is still bewilderingly large, but it's at least manageable by foot. The labyrinthian market is lined with stalls selling fresh meat, produce and spices; shops offering housewares; restaurants cooking up little snacks or antojitos; and bars serving drinks and less savory things. As with much of Mexico City, it's wise to guard against pickpockets, but keep your eyes open and enjoy one of the greatest spectacles Mexico City has to offer.