But by far the best example of a forebuilding is to be found at Dover, standing against the eastern face of the great Keep. It is so designed that three separate protections are afforded to the stairway leading into the Keep, the base, centre, and landing stage having each a separate tower for its defence. The entrance upon the first floor is barred by a door of formidable thickness and great strength; upon the first floor occurs the Chapel, and a view into it is obtained from the stairway, while a small chapel or oratory is placed overhead upon the second floor. A well, now disused, formerly had its opening in the third floor. The actual entrance to the Keep occurs upon the second floor, although an ancient one, now blocked up, opened to it from the first floor. _Dover Castle_, from its commanding position at the narrowest part of the English Channel, has for many centuries occupied one of the most prominent positions among the fortresses of England. It stands upon a chalk knoll to the east of the town, and by nature and art is practically severed from the adjacent land, whether high or low. From traces, which are now almost entirely obliterated, it is concluded that a Celtic defence primarily existed upon the summit; this was followed after A.D. 42 by a Roman station, the chief remains of which are to-day embodied in the well-known Pharos, a companion probably to that erected in A.D. 40 by Caligula upon the Gallic shore. Traces of the Roman occupation, apart from the lighthouse, are very scanty, and are overshadowed by the Saxon work, although it is open to doubt whether the development of the latter was carried out to any elaborate extent. [Illustration: DOVER CASTLE, KENT.] It is with the Norman period that the history proper of the Castle commences. It surrendered without opposition to the Conqueror, who added to the defences, and it was able to resist a sharp attack upon it in 1074 when the men of Kent rose against William. Shortly after this the town was surrounded by walls. [Illustration: DOVER CASTLE.] Although Dover was rightly considered as the key of England, the fortress is not connected with many of the great events which have gone to make the history of England. It has always been in the possession of the Crown and governed by a Constable. Hubert de Burgh defended it against the Dauphin in the time of King John, and, although Louis built many trebuchets and imported minor petraries from France, these, combined with beffrois, sows, and rams, failed to shake his determined defence. Dover appears to have played but little part in subsequent history, probably through its falling into ruin by neglect during the "Wars of the Roses" and of the great Rebellion.