The towers are placed at suitable intervals to enable the curtains to be defended from them by lateral fire, and some of them are strengthened with a projecting beak to prevent the sappers from approaching when the angle could not be well commanded from the adjoining parapets, as is the case in the tower at the N.W. angle of the walls seen in Fig. 111. One large square tower (shown in Fig. 111) called the “Tour de l’Evêque” joins the outer and inner enceintes together by bridging over the space between them. It has thus complete control over the lices both from apertures in the vault, and from the hoardings which were projected on the flanks. This tower derives additional interest from having been used by Viollet-le-Duc as his studio while superintending the work of restoration, and it contains a number of fine plaster casts prepared by him. The parapet walk of the inner wall runs all round the battlements. In some cases it is interrupted by the towers (Fig. 114), and passes through them; in other cases it is carried round the exterior of the towers on the side next the town,--the former towers being posts for guards and sentinels, and the latter being intended to serve as independent posts for defence. Access to the walls is provided by good open stairs on the side next the town, as shewn in Fig. 114, which represents the interior of the walls at the same place, as Fig. 113 shews the exterior. [Illustration: FIG. 114. CARCASSONNE--INTERIOR OF WALLS.] The ramparts of Carcassonne have been to a large extent restored within recent years; but still remain untouched on the eastern side (_see_ Fig. 112), where houses have been erected against the inner and upon the top of the outer walls, so as to convert the “lices” into a street. On this side the walls of the town are separated from the surrounding land, which here is rather high, by a wide and deep ditch. The high ground beyond the ditch was originally fortified with a large round tower (now destroyed) which is supposed to have communicated with the town by a subterranean passage. Above the old houses on the walls are seen rising the great towers of the Porte Narbonnaise, each strengthened with a salient beak. Between these towers is the gateway. It had no drawbridge, but was defended in front by a great chain, a wide machicolation, a portcullis, and folding gates. In the centre of the vault over the archway there was a large opening, and the inner gateway was strengthened with a wide machicolation, a second portcullis, and a second gate. Besides these the towers were of course provided with their hoardings and a _bretêche_ projected over the gateway. The great angle tower, called the “Trésau,” and a large angle bartizan further protected the approach of the gateway, as seen in the sketch.