From the river bank a few yards above the bridge it is easy to form an idea of what the great Norman fortress was. The lofty mound upon which the Keep was built, perhaps a prehistoric tumulus in its origin, is still the most prominent object, though all vestiges of the tower and its outworks have now disappeared, giving place to a luxuriant growth of forest trees. Close beside this mound, traces of the southern moat are to be seen, opening out upon the ditch which still separates the castle grounds from the meadow beside the river. The broken ground rising within the ditch shows the line of the eastern front of the castle with its projecting bastions overlooking the river, though all that now remains is an ivy-covered ruin with the opening of a large window, known as the Queen's Tower. In the background, and more to the right, is another fragmentary ruin, forming a central portion of the north wall; while a modern boat-house marks the outflow of the moat at its north-eastern angle. From this point along the northern front a triple entrenchment is clearly shown by the undulations of the ground; the innermost ditch, close beneath the wall, being the moat of the Castle itself, while the second is the moat of the Castle precincts enclosing a space of intermediate ground on the west and south, and the outermost is the moat which enclosed the whole town; the three being brought close together in parallel lines along this side of the Castle. It must have been from this point of view, that Leland, in Henry the Eighth's reign, described the Castle as having "three dikes, large, deep, and well watered; about each of the two first dikes are embattled walls, sore in ruin and for the most part defaced; all the goodly buildings, with the towers and dungeon, be within the three dikes." Camden, who tells that "the size and magnificence of the Castle used to strike me with amazement when I came hither, a lad, from Oxford," describes it more accurately as "environed with a double wall and a double ditch." South of the great mound and its protecting moat is the ruined tower and south wall of the Collegiate Church of St. Nicholas, now surmounted by a modern turret; and adjoining it are some fragments of the other buildings of the college, with a good doorway and some windows of perpendicular character. Beyond these ruins a large portion of the second moat is to be seen. The south-western angle of the precincts, with the banks of the moat well preserved before it and behind it, is occupied by the modern dwelling-house. Lastly, near the north-western angle, where this outer precinct ends, the site of Brien Fitzcount's dungeon is shown; and the remains of it, with massive rings fixed to the stonework, existed here within the present century.