Ancient Roman temples are among the most visible archaeological remains of Roman culture, and are a significant source for Roman architecture. Their construction and maintenance was a major part of ancient Roman religion. The main room (cella) housed the cult image of the deity to whom the temple was dedicated, and often a small altar for incense or libations. Behind the cella was a room or rooms used by temple attendants for storage of equipment and offerings.The English word ""temple"" derives from Latin templum, which was originally not the building itself, but a sacred space surveyed and plotted ritually. The Roman architect Vitruvius always uses the word templum to refer to the sacred precinct, and not to the building. The more common Latin words for a temple or shrine were aedes, delubrum, and fanum (in this article, the English word ""temple"" refers to any of these buildings, and the Latin templum to the sacred precinct).Public religious ceremonies took place outdoors, and not within the temple building. Some ceremonies were processions that started at, visited, or ended with a temple or shrine, where a ritual object might be stored and brought out for use, or where an offering would be deposited. Sacrifices, chiefly of animals, would take place at an open-air altar within the templum.