2. Fortified Hill-Tops strengthened. This includes fortresses situated on hill-tops, with artificial defences adapted to the natural configuration of the ground, or to those which are less dependent on the natural slopes.
3. Simple Artificial Enclosures, including rectangular or other forms, and all the fortifications and towns of the Romano-British period.
4. The Mount and Fosse.
5. The Mount and Bailey, consisting of natural or artificial mounds with one or more courts attached.
6. Homestead Moats.
7. Homestead Moats developed, referring to enclosures similar to No. 6 but augmented by supplementary defences.
8. Protected Village Sites.
Class I.—Natural Fortresses strengthened.
This division may very readily be subdivided into three parts dealing with natural fortresses according to the topographical characteristics as follows: