In 1814, the hills around Rancagua were the site of a battle in the War of Independence known as the Desastre de Rancagua (Disaster of Rancagua). Chilean independence fighters, including Chile's independence leader Bernardo O'Higgins, held off the powerful Spanish army for two days before surrendering, but escaping to fight another day. In the resulting blaze, much of the town was destroyed.
Despite its historical significance and current importance as a regional commercial center, the city has relatively little to offer in terms of tourism. By all means, visit the historic area around the central plaza or take in a rodeo in the national Medialuna, or rodeo arena, but otherwise skip the city and head straight for one of the more interesting attractions outside of town such as a copper mine, hot spring, nature reserve, or winery.