and rear walls of Roman temples might be largely undecorated (as in the Pantheon, Rome and Vic), inaccessible by steps (as in the Maison Carrée and Vic), and even back on to other buildings. As in the Maison Carrée, columns at the side might be half columns, emerging from ("engaged with" in architectural terminology) the wall. The platform on which the temple sat was typically raised higher in Etruscan and Roman examples than Greek, with up to ten, twelve or more steps rather than the three typical in Greek temples; the Temple of Claudius was raised twenty steps. These steps were normally only at the front, and typically not the whole width of that. It might or might not be possible to walk around the temple exterior inside (Temple of Hadrian) or outside the colonnade, or at least down the sides. The description of the Greek models used here is a generalization of classical Greek ideals, and later Hellenistic buildings often do not reflect them. For example, the "Temple of Dionysus" on the terrace by the theatre at Pergamon (Ionic, 2nd century BC, on a hillside), had many steps in front, and no columns beyond the portico. The Parthenon, also approached up a hill, probably had many wide steps at the approach to the main front, followed by a flat area before the final few steps. After the eclipse of the Etruscan models, the Greek classical orders in all their details were closely followed in the façades of Roman temples, as in other prestigious buildings, with the direct adoption of Greek models apparently beginning around 200 BC, under the late Republic. But the distinctive differences in the general arrangement of temples between the Etruscan-Roman style and the Greek, as outlined above, were retained. However the idealized proportions between the different elements in the orders set out by the only significant Roman writer on architecture to survive, Vitruvius, and subsequent Italian Renaissance writers, do not reflect actual Roman practice, which could be very variable, though always aiming at balance and harmony. Following a Hellenistic trend, the Corinthian order and its variant the Composite order were most common in surviving Roman temples, but for small temples like that at Alcántara, a simple Tuscan order could be used. Vitruvius does not recognise the Composite order in his writings, and covers the Tuscan order only as Etruscan; Renaissance writers formalized them from observing surviving