- The Castellum was a Roman Fort whereas the Castra was a Roman Camp, Marching Camp or Fortress. These are the definitions that are followed by Classical Scholars.
- The Castra could be either a square or a rectangle and was divided into four equal divisions by two intersecting roads. It was surrounded by four walls with gates and a defensive ditch.
The Roman Fort Grid Plan
- Via Principalis
- In a Fort, the north-south Cardo Maximus was called the Via Principalis.
- North and South Gates
- The Via Principalis had a north gate and south gate, the Porta Principalis Dextra (Right Principal Gate) and the Porta Principalis Sinistra (Left Principal Gate).
- Each gate was fortified with two towers, but whether it was north or south depended on which direction the Praetorium (Base commander’s house) was facing, which could vary.
- Via Praetoria
- This was the east-west equivalent of the Decumanus Maximus, and intersected the Via Principalis creating four equal divisions of the fort.
- East and West Gates
- The Via Praetoria had an east gate and a west gate, the Porta Praetoria (Main gate) and the Porta Decumana or Porta Quaestoria (Supplies gate).
- A Legion marched in via the Porta Praetoria and lined up on the Parade Ground in front of the Praetorium (Commander’s building). The Standards of the Legion were placed on display here.
- The Principia
- This was the Headquarters building with a large Hall for meetings, which also acted as a Temple, and rooms where the administration of the Fort took place.
- It was the largest building in the Fort and held the Arsenal and the Legionary Standards. Underneath was a strongroom for holding cash to pay the Legionaries’ wages.
- In front was a central square which was the Parade Ground and held the Praetorium and officers quarters. Its function was similar to the Forum in a Roman town.
- The Praetorium
- This was the Base Commander’s Building, where he lived and conducted business.
- When he stood outside his house, the Porta Principalis Sinistra was to his left and the Porta Principalis Dextra was to his right. Ahead of him was the main ceremonial entrance to the fort, the Porta Praetoria.
- Valetudinarium
- Valetudinarium means ‘Hospital’ in Latin and these were located on the ‘Latera Praetorii’, meaning to the sides of the Commandant’s Headquarters building.
- Granaries
- Also located near the centre were the military granaries called Horrea, consisting of stone or wooden sheds, which were supported on posts with the Grain kept in Bins. Each fort was supposed to hold six months supply of grain as a precaution against a siege.
- An outline of the base for the Granaries can be found in the South Shields Roman Fort.
- The Legionary Barracks
- These were usually placed close to the Fortress Walls and Gates at one end.
- Each Contubernium (Tent Group) of eight men would sleep in a room together.
- The Cavalry barracks would often be placed at the opposite end of the Fort, with the horses billeted in adjacent rooms to their riders.
- Bathhouse
- This building held the furnace for heating the water and the hypocaust.
- Workshops
- Every Fort held Armories for the production and assembly of Swords, Shields, Bows and Armour, as well as parts for the Artillery machines.
- They had forges and a water supply from the main cistern.
- Cistern
- Capable of holding sufficient water for the whole Fort to withstand a siege.
- The Fort Walls and V-Ditch
- The Walls would be constructed of stone set above sloping ramparts and be capable of withstanding a prolonged siege.
- A double or triple V-Ditch would surround all four walls, to prevent an enemy from approaching and scaling the walls.
Outside the Fort
- Smaller Forts sometimes had the Bathhouse placed outside the Fort.
- A supporting village called the Vicus supplied the Fort, and always grew up outside the Walls.
Legionary Fortresses of the Roman Empire
- The Ruins of many Roman Forts around Europe can be visited and the outline of their streets and buildings are still visible.