Its main structure is of late fourteenth century date. Elaborate and complicated defences guarded the main entrance to the mediaeval castle. Before the unwelcome visitor could enter, the following obstacles had to be surmounted. First was the gateway in the outer wall of defence, access to which was by means of a drawbridge spanning a deep but perhaps dry moat. This first gateway was furnished with portcullis, and heavy timber doors capable of offering formidable resistance. The outer gateway passed, the invaders would proceed across the outer bailey towards the inner and far stronger gatehouse, exposed all the while to such missiles, arrows, cross-bow bolts, etc., as might be projected from the battlements and loop-holes of the castle. Here, at the entrance to the great gatehouse, the moat was generally wide, deep, and filled with water. Supposing that the drawbridge was down (a most unlikely circumstance), the enemy on approaching the gates was confronted by the massive portcullis, and at least two pairs of double timber gates beyond it, and whilst forcing the former he would be within the range of heavy stones and every kind of dangerous and unpleasant missile dropped or thrown from the machicolations situated between the flanking towers almost on a level with the battlements above. The massive and studded oak doors were constructed of a material which was not easily fired, and they were barred with oak beams of the strength and almost the consistency of steel. Even when these were burnt or battered down the invaders would encounter a flanking fusilade from the lateral passages. On the other hand, if the drawbridge was up, it formed in itself an extremely formidable barrier, because by means of chains passing through holes in the wall it was drawn close to the gatehouse tower and within the recess specially made to receive it, leaving the under side of the bridge flush with the surface of the gatehouse wall. It may be doubted whether anything in the whole range of military architecture furnishes a more perfect system of defence than the gateway, walls, ditches, moats, and drawbridges of a mediaeval castle; and it seems probable that it would have proved invulnerable against a direct attack from without had not the discovery of gunpowder put a new and terrible weapon in the hands of the attacking force.