Many castles were placed on the sites of Saxon strongholds, and of strongholds dating from still earlier times. Others were built where the overlord thought they would be of service to him in protecting his interests and keeping his tenants in order. So it often came to pass that the castles were built close to, or in the very heart of, a town or city. Frequently the castle was at once the protection and the terror of the neighbourhood. It is curious to note that some of the greatest castle-builders of the time were bishops. There was Bishop Gundulph of Rochester, who built the Keep of Rochester Castle and the White Tower in the Tower of London. There was Bishop Henry de Blois of Winchester, who built a number of castles on lands belonging to his bishopric. Strange as it may seem to us that bishops should be great rulers and leaders of armies, it did not strike the people of those days as at all extraordinary or improper. A bishop was as much a ruler as the king, and had territories to look after and keep in order. In those days he was quite as able to carry out these duties as the boldest baron of them all, and could give and take hard knocks with the best of them. [Illustration: _Rochester Castle: The Keep_ _Rochester Castle was built by Bishop Gundulf between 1077 and 1108, under the order of William Rufus. The magnificent Keep (70 feet square and 104 feet high) was added about 1126._] The great castle-builders had no love for the traders in towns and cities; indeed they looked down on that class. But they found them very useful. Towns attracted traders by land and by water; and every town, every bridge, and every ferry belonged to some lord or other. No goods could be brought into or taken from a town, or carried across bridge or ferry, without paying toll and custom to the overlord. But he had certain duties to perform in return, in protecting the town and its trade; and the better the protection the more traders came to pay toll, and the better it was for everybody concerned. So we find, near many of our ancient towns and cities, a castle, or its ruins--or perhaps only the site is left--where the lord of the town kept a number of men to protect the town and district, even when he was not there himself. If there was no love lost between the lord of the castle and the townsmen, there was still less between the latter and the soldiers. The soldiers were inclined to take liberties, and to be insolent and oppressive. As they had it in their power to "make trouble", if not kept in good-humour, the townsmen put up with much for the sake of peace and quietness. [Illustration: _The White Tower, Tower of London, built by Gundulf, Bishop of Rochester, 1078. The exterior was restored by Wren, but within the Norman work is little altered_] CHAPTER XX Castles and Towns