Olèrdola castle controlled the area of the Penedès Depression in the Early Middle Ages, reaching the height of its significance when its castle dominated the region under the control of the rebellious Mir Geribert, "Prince of Olèrdola". Its importance declined from the twelfth century and its administrative role was taken by Vilafranca del Penedès. The territory has been inhabited since the Neolithic period, and Iberic and Roman remains are juxtaposed with the ruins of the castle. The unusual, circular, roman chapel of the Sant Sepulcre is near La Plana Rodona.
The name of the municipality is derived from the historical castle, not from any modern settlement. Six villages and two industrial zones (polígons industrials) make up the municipality. Populations are given as of 2005: