Guanajuato is simply gorgeous. It spills across cliffs and hillsides down to a series of tree-shaded plazas whose sidewalk cafés and street life are unmatched in any comparably sized town in Mexico. The city's street plan is nearly inscrutable—roads never seem to end up where you'd expect, and are intersected by dozens of alleys—but getting lost for a few hours will be an adventure rather than a nuisance. You’ll see fewer gringos here than in San Miguel de Allende; the majority of tourists are Mexican. But that could be said of any of the heartland cities except San Miguel.
Once the most prominent silver-mining city in colonial Mexico, Guanajuato is in a gorge surrounded by mountains at 6,700 feet. Its cobblestone streets, which are peppered with colorful houses, wind precipitously up the mountainside. The city's other distinguishing feature is a vast subterranean roadway, where a rushing river once coursed through the city.
The city was settled by wealthy land- and mine-owners, and many of its colonial buildings date back to the 18th century. Those buildings around the center of town have become museums, restaurants, hotels, and government offices. Add to this its many imposing churches, plus the green-limestone University of Guanajuato, originally a Jesuit seminary, and it's no wonder the town was named a World Heritage Site in 1988.
One thing you don't need in Guanajuato is a car. Guanajuato's streets are often clogged with traffic, and you can find yourself stuck in an exhaust-filled tunnel waiting for traffic to clear, or hopelessly lost. It's easy and much more practical to stroll the city center on foot and let cab drivers figure the rest of it out. The two main arteries, Avenida Juárez and Positos, change names frequently, but from these, along with intersecting streets and callejones (alleys) you can access the main sights. A good map is essential; stop by the tourism office when you first get to town.
Start your exploration of Guanajuato with a ride on the cable car, or funicular (behind the Teatro Juárez). The short trip across the gorge to the statue of El Pípila provides wonderful views and photo ops of this colorful town. If you study your map, you'll be able to identify most of the important buildings, like the university, the cathedral, and the Mercado Hidalgo. This perspective may come in handy later, when the curving streets spin you around.
A walk around the center of town can take anywhere from a couple of hours to the entire day. Remember that most museums and the theater are closed Monday.