ANTICUM, in Ancient Architecture, the front door of a house, called also janua, and in Greek by the several terms θύρα ἀνδρεός, ἀνδρεα, ἀνδρα. The back door in Roman houses was called posticum, postica, or posticula, in Greek παράθυρα or παράθερον; and Cicero (Post Red. 6) uses pseudothyron in contradistinction to janua. It was accounted ominous to set the left foot on the threshold; hence the steps of a temple were of an uneven number, so that by commencing the ascent with the right foot, the danger would be avoided. (See Vitruvius, iii. 4.) The door of a temple was called foris and valva, in Greek σπίς, κλισίας, or θύρα, these words being generally used in their plural form to denote the two halves of a folding-door. Bivalve doors were also used in private apartments.