Rancagua sits in the Central Valley 85 kilometres south of Santiago, a working city of around 250,000 people on the banks of the Cachapoal River. Founded in 1743 by José Antonio Manso de Velasco, it is best known for the Desastre de Rancagua in 1814, when Chilean independence forces were overwhelmed by royalist troops in the central plaza — a defeat that sent the independence movement into exile before its eventual triumph. The Plaza de los Héroes and the nearby Iglesia de la Merced — O'Higgins's wartime command post — still mark the spot.
The city's other claim to fame is El Teniente, the world's largest underground copper mine, high in the Andes above town. The old mining camp of Sewell, now a UNESCO World Heritage Site, clings to the mountainside at 2,000 metres and can be visited on day trips from Rancagua. The surrounding O'Higgins region is wine country — the Cachapoal Valley produces some of Chile's best reds — and Rancagua itself is the spiritual home of Chilean rodeo, with the Medialuna Monumental hosting the national championship every year.