In architecture the great characteristic is the quaint way the houses have been built. The streets have been cut out of the rock below the general surface of the land. The houses appear to have been built into the rock, or rather to have been piled up against it. The shops are level with the streets, and over them runs a balustraded gallery. Steps at certain intervals lead the way down into the streets. These galleries are called by the inhabitants "The Rows." These Rows are houses with shops. Overhanging the shops, like the eaves of a house, are the upper stories, to which additional flights of steps give access. Two explanations are given for this unusual construction of houses: one, that the Rows, or promenades, are the remnants of the ancient vestibules of the Roman houses; the other that they were probably originated to afford ready defence against the sudden raids of the Welsh. The latter appears the more likely. The Rows, from their position to the streets, would afford the besieged greater facilities of shelter and attack. In Bridge Street and Eastgate Street the Rows are made pleasant promenades. Though many of the houses have been rebuilt, they still retain the old character. In addition to these interesting buildings there was the castle built by the Conqueror, of which there remains only a large square tower, called "Julius Agricola's Tower." The front has been entirely renewed. This tower served probably as a place of confinement of the Earl of Derby. Here were imprisoned Richard II. and Margaret, Countess of Richmond. Just shortly before the Revolution James II. heard Mass in the second chamber. Though the Cathedral has been left to the last, its history is no less interesting than the other features of Chester. The Cathedral was originally the church attached to the convent of St. Werburgh, under which name its ecclesiastical site is mentioned in "Doomsday Book." It was first dedicated to St. Peter and St. Paul, but Ethelfrida afterwards transferred their patronage to that of the Saxon saint, Walmgha, the daughter of Wulphen, King of Mercia. Besides this princess the great benefactors were Leofric, Earl of Mercia, and Hugh Lupus, who substituted Benedictine monks for secular canons.