In the centre of the East – West roadway lie the remains of a small square building. This is the Principia or Command and Administration headquarters. The Principia was also the spiritual centre of the fort and the central room would contain the regimental shrine as well as a sunken pit which acted as a ‘strong room’ for the regimental pay chest. The money was kept here as a deterrent to thieves who would be committing sacrilege if they stole from the shrine.