The largest city along Highway 57 is San Luis Potosi, capital of the state of the same name. The main highway by-passes the city by a mile or so; if you make the side trip into town, you'll consider your time well spent.
A rich mining center since the 1600s, San Luis Potosi is also a modern industrial city and a major rail center. Here, too, is the Mexican plant of another well-known U.S. firm-Allis Chalmers.
The local bazaar, Hidalgo Market, offers good buys in rebozos, locally made pottery, and regional handicrafts. The Chamber of Commerce displays an interesting selection of crafts from the stateand it is all for sale. You'll probably have a chance to sample prickly pear or tuna cheese here.
Of interest, also, are the cathedral, the Church of Our Lady of Carmen, and the famous Caja de Agua the small, round wellhouse designed by Tresguerras which serves as the hub of the city's water system.