A Roman camp was usually square, with the corners slightly rounded, as has been proved by the excavations at Melandra and by the piece of Roman wall lately discovered at Chester, which shows a distinct curve towards the Pepper Gate. Roads crossed the camp at right angles. The wall or 'vallum' was protected when necessary by a fosse or ditch, but Agricola chose his positions with such care that one side at least was usually already guarded by the waters of some stream. Watch-towers were placed at the corners and on either side of the gateways.
Chester still preserves the shape and plan of the Roman fortress. Its four main streets, which are hewn out of the sandstone on which the city is built, cross each other at right angles. The Welsh called it Caer Lleon or Lleon Vawr--the 'Camp of the Legion'. The present walls are not, however, the work of the Romans, though here and there they have been proved to have been built on the foundations of the Roman walls. The lowest courses of the North Wall near the Deanery Field, when excavated, were found to be faced with massive stones of Roman masonry, with a Roman 'plinth' running along the base. The stones fit very closely together and no mortar was used. The inside of the wall was filled with rubble.
From time to time portions of Roman wall have been found in other parts of the city. One big piece is in the cellars of Dickson's seed warehouse. When the foundations of the offices of the National Telephone Company in John Street were being excavated a year or two ago, a fine piece of Roman wall was unearthed. The builders have left it standing where they found it, and you may now see it in the basement of the building, protected from future harm by an iron grid.
On the Roodee is a portion of Roman masonry of finely jointed stones which is thought to have been the quay of the Roman city.
In the middle of a Roman fortress was the Praetorium or general's quarters. Traces of such a building are to be seen in the camp at Melandra, and at Chester the foundations of a large edifice discovered in Northgate Street may possibly be a portion of a similar building.
Inscriptions show us that another legion, called the Legio Secunda, was stationed at Chester for several years. When Britain was more or less pacified and required fewer troops this legion was recalled and sent to the Roman provinces on the Danube.