Rancagua ’s Andean backcountry, little visited even by Santiaguinos, offers some exceptional excursions:
In town, Rancagua ’s historic center is the Plaza Los Héroes; though no colonial buildings remain here, it is newly and pleasantly car-free. Its main landmarks are the neoclassical Gobernación Provincial (1889), a national monument, and the Iglesia Catedral (1861) at the south end. On and around the plaza are several monuments, including a banal equestrian statue of Bernardo O’Higgins and a hideously stylized stone sculpture of city founder (and later viceroy of Peru) José Manso de Velasco.
One block north, O’Higgins and his troops occupied the late 18th-century Iglesia de la Merced (Estado and Cuevas) during the battle of Rancagua . From the tile-roofed adobe’s tower, O’Higgins watched hopefully for reinforcements, but two-thirds of his troops perished here.
At opposite corners of Estado and Ibieta, two late colonial houses, both national monuments, together form the Museo Regional (tel. 072/221524, www.museorancagua.cl ). The more distinctive is the Casa del Pilar de Esquina (Estado 684), with exhibits on local prehistory, mining, and agriculture. Named for the corner pillar often used as a colonial architectural flourish, it was owned by independence figure Fernando Errázuriz Aldunate, Rancagua ’s representative to the Congress of 1811. Hours are 10 a.m.–6 p.m. weekdays except Monday, 9 a.m.–1 p.m. weekends and holidays. Admission costs US$1.10 for adults, US$0.55 for children, but on Tuesday and Sunday it’s free.
The Casa del Ochavo (Estado 685) is filled with period furniture and colonial religious art, as well as an almost equally devotional tribute to O’Higgins’s role in Chilean independence. Hours and admission fees are the same as the Casa del Pilar de Esquina.
One block south, the Casa Patronal del Ex Fundo El Puente (Av. Millán and Av. Cachapoal) was the landowner’s residence that housed royalist Colonel Mariano de Osorio during the Battle of Rancagua  (Osorio’s victory earned him the viceroy’s appointment as governor of Chile, a position whose power he wielded ruthlessly). Also a national monument, it now holds the city’s Casa de la Cultura, which occasionally exhibits paintings and photographs.