Praetoria Augusta (castra)

Praetoria Augusta was the Roman military camp (castra) that eventually developed into the city of Aosta in the Aosta Valley region of northwestern Italy. Founded in 25 BC by Aulus Terentius Varro Murena, it was established as a strategic outpost during Augustus' campaign to subdue the Salassi, a local Celtic tribe who controlled the important mountain passes between Italy and Gaul.

The castra was laid out in a typical Roman grid pattern, encompassing a rectangular area of approximately 396 x 576 meters. This enclosed area accommodated around 3,000 soldiers, primarily from the cohors praetoria, hence the name "Praetoria Augusta," meaning "Augustus' Praetorian camp." The strategic location at the confluence of the Dora Baltea and Buthier rivers, and its position controlling access to the Little St Bernard Pass and the Great St Bernard Pass, made it a crucial point for Roman control of the region.

The camp included the essential structures for military life, such as barracks, storehouses, a headquarters (principia), and a hospital. Defensive walls, constructed from large stone blocks, and fortified gates protected the camp. Over time, as the area became more pacified, a civilian settlement began to grow outside the castra, attracted by the security and economic opportunities offered by the military presence. This led to the eventual transformation of the castra into a thriving Roman city. The present-day city of Aosta still retains much of the original Roman street plan and features significant Roman ruins, including sections of the city walls, the Arch of Augustus, a theater, and an amphitheater, providing substantial evidence of its origin as the military camp of Praetoria Augusta.