The death of the Conqueror, however, in 1087, about eight years after he had commenced this fortress, for some time prevented its progress, and left it to be completed by his son William Rufus, who, in 1098, surrounded it with walls and a broad and deep ditch, which is in some places about one hundred and twenty feet wide, into which water from the river Thames was introduced. Henry III., in 1240, ordered a stone gate, bulwark, and other additions to be made to this fortress, and the ancient tower to be whitened, from whence it was called the White Tower. In 1465, Edward IV. greatly enlarged the fortifications, and built the Lion's Tower, for the reception of foreign beasts, birds, &c., presented to the kings of England; the zoological collection have, however, long since been transferred to more eligible quarters in the Regent's-park. By the command of Charles II., in 1663, the ditch was completely cleansed, the esplanade rebuilt with brick and stone, and sluices were erected for admitting and retaining water from the Thames, as occasion might require. The Tower is in the best situation that could have been chosen for a fortress, lying near enough to protect the metropolis and the seat of commerce from invasion by water. It is parted from the river Thames by a commodious wharf and narrow ditch, over which is a drawbridge. Upon this wharf is a noble platform, on which are placed sixty-one pieces of cannon, nine-pounders, mounted on handsome iron carriages, which were fired on state holidays, but small pieces are now used for those purposes. Parallel to the middle part of the wharf, upon the walls, is a platform, seventy yards in length, called the Ladies' Line, from its being much frequented in the summer evenings, as on the inside it is shaded with a row of lofty trees, and without affords a fine prospect of the shipping and of the boats passing and repassing on the river. The ascent to this line is by stone steps, and, being once upon it, there is a walk almost round the walls of the fortress without interruption, in doing which the visiter passes three batteries: the first called the Devil's Battery, where there is a platform on which are mounted seven pieces of cannon; the next is named the Stone Battery, and is defended by eight pieces of cannon; and the last, called the Wooden Battery, is mounted with six pieces of cannon.