Very often the modern engineer has misunderstood their origin, and, regarding them as decorations, he has used safety recesses to ornament his wide bridges, just as he has put battlements on iron parapets and stuck machicolations on defenceless gateways. Brangwyn has drawn for us three or four big Gothic bridges with safety recesses. Among them is a fine structure over the Main at Würzburg, in Bavaria; there are eight arches, and the length is 650 ft. This bridge dates from the year 1474, but his adornment with statues of saints belongs to later times. Indeed, the architecture and decoration take us from the end of the Middle Ages to the year 1607, when the spirit of the Renaissance was active and generative. [Illustration: THE BRIDGE OVER THE MAIN AT WÜRZBURG IN BAVARIA (1474-1607)] Here is an old defensive bridge that does not resemble a common man-at-arms: in him there is a fine courtesy, as of a knight long used to the etiquette of tournaments; but yet the technical inspiration is rather inferior to that in his great rival, the Moselle Bridge at Coblentz, built in 1344, by the Elector Baudouin, and charmed with a mellow grace that imparts a rare distinction to the vigour of fourteen bold arches. The Moselle Bridge is 1100 ft. long, or ninety-five longer than London Bridge. There is but one fault, and this one fault belongs to the Middle Ages: the ten piers obstruct the river too much, and two or three of them might have been omitted without harm to any strategic consideration. In the Middle Ages almost everything was looked at from the standpoints of attack and defence. Bridges as well as soldiers needed armour, so their gateways and towers were built in a military fashion, and at times curious traps were devised along the footways. For example, consult the “Pacata Hibernia,” and you will find an engraving of Askeaton Bridge,[112] with a sort of hangman’s trapdoor at each end of the footway. In 1586, or thereabouts, Askeaton Bridge had another peculiarity: a castle stood close to it on an island in the river; and between the castle and the bridge was a fortified platform with two gateways. It happened often, in mediæval times, that one arch was a drawbridge. Take Old London Bridge as an example. One of her twenty arches--the thirteenth from the City end--was a toll-gate for merchant shipping, and a drawbridge to gap off enemies from the town. It served this latter purpose in 1553, when Sir Thomas Wyatt and his insurgents tried to enter London. Everybody knew which was the movable arch, because it was connected in all popular talk with the tower that rose beside it, a terrible and gruesome tower, for on its summit executioners displayed the heads of decapitated persons, who ranged from common bandits to the great Sir Thomas More.