Rancagua's main draws are its compact colonial core around the Plaza de los Héroes and the day trips it offers into copper-mining and wine country. The 1814 battle that made the city famous is commemorated in the central plaza, and the surrounding streets retain a handful of colonial-era houses and churches. Most visitors come for what lies outside town: Sewell, the abandoned mining camp clinging to the Andes; El Teniente, the world's largest underground copper mine; and the Cachapoal Valley vineyards. Save half a day for the city itself and use the rest as a base.