Guanajuato's centre is small enough to walk in a day, but the steep alleys and the surprising depth of the museums and churches make it worth several. Start at the Jardín de la Unión and the Teatro Juárez, walk up through the alleys to the Pípila monument for the long view, then back down past the Alhóndiga and the Mercado Hidalgo. Save the silver-mining sites of La Valenciana for a second day.