Somewhere in the second half of the fourteenth century, then, in the reign of Karl IV., they began to build the outer enceinte, which, although destroyed at many places and broken through by modern gates and entrances,[29] is still fairly well preserved, and secures to Nuremberg the reputation of presenting most faithfully of all the larger German towns the characteristics of a mediæval town. The fortifications seem to have been thrown up somewhat carelessly at first, but dread of the Hussites soon inspired the citizens to make themselves as secure as possible. In times of war and rumours of war all the peasants within a radius of two miles of the town were called upon to help in the construction of barriers and ramparts. The whole circle of walls, towers, and ditches was practically finished by 1452, when with pardonable pride Tucher wrote, “In this year was completed the ditch round the town. It took twenty-six years to build, and it will cost an enemy a good deal of trouble to cross it.” Part of the ditch had been made and perhaps revetted as early as 1407, but it was not till twenty years later that it began to be dug to the enormous breadth and depth which it boasts to-day. The size of it was always a source of pride to the Nurembergers, and it was perhaps due to this reason that up till as recently as 1869 it was left perfectly intact. On the average it is about 100 feet broad. It was always intended to be a dry ditch, and, so far from there being any arrangements for flooding it, precautions were taken to carry the little Fischbach, which formerly entered the town near the modern Sternthor, across the ditch in a trough. The construction of the ditch was provided for by an order of the Council in 1427, to the effect that all householders, whether male or female, must work at the ditch one day in the year with their children of over twelve years of age, and with all their servants, male or female. Those who were not able to work had to pay a substitute. Subsequently this order was changed to the effect that every one who could or would not work must pay ten pfennige (one penny). There were no exemptions from this liturgy, whether in favour of councillor, official, or lady. The order remained ten years in force, though the amount of the payment was gradually reduced.
Whilst the enceinte was in course of erection the Burggraf Frederic VI. sold (1428) to the town the ruins of his castle. Steps were immediately taken therefore to fortify the whole of the Castle grounds with ditch and large revetted circular bastions. Paul Stromer was the director of the works. At this time we first find distinct mention of the Vestner Thor, and the Vestnerthorbrücke. The other main gates, the Neue Thor, the Spittler Thor, the Frauen Thor, and the Laufer Thor had begun to be built about 1380.
The Wührderthürlein and the Hallerthürlein were constructed probably about the same time as the Vestnerthor—i.e. circ. 1430. It was against the gates that the main attacks of the enemy were usually delivered, and they were therefore provided with the most elaborate means of defence. Each principal gate in fact was an individual castle, a separate keep: for it was defended by one of those huge round towers which still help to give to Nuremberg its characteristic appearance. The Laufer, Spittel, and Frauen towers, and the tower near the new gate were built in the above order in their present cylindrical shape (1555-1559) by the architect George Unger, on the site of four quadrilateral towers that already existed. The towers are about 60 yards in diameter. They are furnished on the ground story with one or two gun-casemates, which would command the parapet wall if that were taken. Above, beneath the flat roof, is fixed a platform blinded with wood relieved by embrasures capable of receiving a considerable number of cannon. Guns indeed were in position here as recently as 1796, when together with all the contents of the arsenal they were removed by the Austrians.
At the time of the construction of these and the other lofty towers it was still thought that the raising of batteries as much as possible would increase their effect. In practice the plunging fire from platforms at the height of some eighty feet above the level of the parapets of the town wall can hardly have been capable of producing any great effect, more especially if the besieging force succeeded in establishing itself on the crest of the counterscarp of the ditches, since from that point the swell of the bastions masked the towers. But there was another use for these lofty towers. The fact is that the Nuremberg engineers, at the time that they were built, had not yet adopted a complete system of flank-works, and not having as yet applied with all its consequences the axiom that that which defends should itself be defended, they wanted to see and command their external defences from within the body of the place, as, a century before, the baron could see from the top of his donjon whatever was going on round the walls of his castle, and send up his support to any point of attack. The great round towers of Nuremberg are more properly, in fact, detached keeps than portions of a combined system, rather observatories than effective defences.[30]