The principal entrance to the palace is on the west side, and opens from an esplanade which commands the surroundings, and was formerly divided into several baileys or courts, with walls, towers and gates. The entrance gateway was defended with two portcullises, with folding gates and double machicolations. It had originally an advanced work in front, which was replaced in the seventeenth century by a crenellated wall. The appearance of the building, whether it be regarded externally or from the courtyard, is grand and imposing from its vastness and height. The towers and walls are, even in their present crippled condition, most commanding from their magnitude, the former being about 150 feet in height, while the walls rise to about 100 feet. On entering the great courtyard (D), evidence presents itself of the difference in level between it and the older northern court (C), in the rugged foundation on which the south front of the latter stands, the rock having been cut down, as above mentioned, to the level of the lower court. The frowning machicolations of that side, which look somewhat out of place in a _Cour d’honneur_, are explained when we remember that under Pope Benedict XII. this formed the exterior of the south face of the palace, before the south courtyard was added by Clement VI. and Innocent VI. The most striking feature of the architectural details of the palace is the machicolations of the parapet. These consist in long grooves opening between the inside of the parapet and the external face of the walls, the parapet being carried on pointed arches thrown between buttresses which project at intervals (_see_ Fig. 47). This form of machicolation (which we have already observed at Cruas) is much used in the southern provinces, perhaps from the prevalence of such works in the churches, most of which were fortified, and where the buttresses which existed for other reasons, were found convenient, and were thus utilized. These long machicolations have the advantage of allowing beams, and other lengthy missiles to be thrown down on assailants; but the frequently recurring broad buttresses or wall spaces, which have no defence immediately over them, are a drawback. In the North these long grooves are very rarely used; a continuous series of machicolations between bold corbels being the form almost invariably preferred. At Avignon the towers were crowned with the latter kind of defences, as the relics of the broken corbels still shew. The _Cour d’honneur_ communicates freely with every part of the structure. To the right, on entering, is observed the arcade which contains the great staircase leading in two flights to the principal apartments on the first floor. Two posterns open from this courtyard, and these are carefully masked in the re-entering angles by buttresses, and defended with a portcullis. A staircase also leads to the upper courtyard.