Simultaneously with the alterations of the exterior wall small bastion-like towers were also constructed, chiefly at places where the wall formed an angle, and where the enemy could not therefore advance in line. From these towers a searching fire could be maintained in all directions, sweeping both the ditch and the ground in front. The strong, low, semi-circular tower at the Haller Thor is supposed to be the oldest work of this description. Lastly, in the second half of the sixteenth century, the large bastions which bring us in touch with modern ideas of fortification were built. We may instance the bastion adjoining the Neue Thor, called the Doktors Zwinger because the doctors had their summer garden there. And in 1613 the Vöhrderthor-Zwinger was added to the old town-wall. It was designed by Meinhard von Schönberg, and built by Jakob Wolf, the younger. But in 1871 this magnificent structure, with the armorial devices which decorated the four corners of it, was enclosed in the Vestner Thor Zwinger. An account of the fortifications of Nuremberg would be incomplete if no mention were made of the _Landwehr_--a continuous line of defence which was thrown up at some little distance from the town about the middle of the fifteenth century, in the time of the first Marggravian war. The _Landwehr_ was a ditch with an earthen parapet strengthened by stockades, barricaded at the crossings of the roads with obstacles and moveable barriers, and defended by blockhouses in which guards were always kept. The main object of this fortification was to afford shelter to the country people, and to secure them and their goods and cattle from the raids of the enemy. Only the merest fragment of the "Land-ditch" remains, viz., the Landgraben, running through the Lichtenhof meadow. It will be gathered from these dry details that the chief note struck by the fortifications of Nuremberg is that of picturesque variety. The defences have been built at different times and form no stereotyped pattern. Walls, towers, and bastions of varying types and shapes, suggesting the ideas of different ages, succeed each other in pleasant confusion. The walls themselves, now high, now low, now with, now without roofing, here crenelated with narrow loopholes and arrow-slits, there fitted with broad embrasures for heavy guns, seem to be typical of the place and to suggest to us the recollection of her chequered career.