The Plaza de Armas is the heart of Saltillo's colonial centre, a large shaded square flanked by the cathedral to the south, the Palacio de Gobierno to the west, and the Palacio Municipal to the north. In the evenings the square fills up — families with strollers, vendors selling corn and sweets, old men on benches. It feels genuinely lived-in rather than preserved for tourists.
The Palacio de Gobierno — known informally as the Palacio Rosa for its pink quarried stone facade — is worth looking at closely. The building dates from the colonial era and houses murals depicting the history of Coahuila on its interior stairways. Entrance is free during business hours and guards generally wave visitors through.