Principia Museum

Principia Museum in Alba Iulia is a rare opportunity to step directly into the heart of a Roman military headquarters. Built over the original principia of the ancient fortress of Apulum, the museum preserves the very stones once walked by legionaries of Legio XIII Gemina. Its modern glass-and-steel structure protects the archaeological remains while allowing visitors to see them exactly where they were discovered. The main attraction is the central courtyard, where the outlines of Roman walls and columns reveal the layout of the command centre. You can clearly identify the flag sanctuary, the most sacred room of any Roman fort, where standards and imperial portraits were kept. Nearby, the tribune’s office shows how military administration functioned nearly two millennia ago. Glass walkways guide you above the ruins, offering close views of inscriptions and carved stones left by soldiers, officers, and craftsmen. Interactive displays explain daily life in the fortress, from logistics to religion. A highlight is the 3D reconstruction area, where visitors can visualise how Apulum looked at its peak.