This diagram shows the principal landmarks. The camp was formed by intersecting roads, with gates at the end of each. The main building of the camp was the Principia, located at the intersection of the two main roads.
The walls of the camp were designed to neutralize an attack. The first step in building them was to dig a trench six feet deep. When the trench was complete its sides were graded into a “V” to prevent an attacker from jumping across. The soil from the trench hole was then piled into a rampart frame of logs, making the total thickness of the rampart 3-5 meters. The top of the rampart was covered with palisades to produce a fence. Each legionnaire carried two 6 foot palisades in his kit which were tied together when placed.