Excavations on the outskirts of Sofia, Bulgaria, have revealed an expansive 2nd-century Roman cavalry fort that once guarded the strategic borders of ancient Serdica. The most significant find at the site is a cache of gilded iron armor, including a rare and exceptionally well-preserved decorative cavalry mask featuring intricate mythological scenes of Mars and Minerva.
The fort appears to have been a major military and administrative hub, featuring a central principia (headquarters) building with intact mosaic floors and several barrack blocks. The presence of such high-status armor suggests that an elite 'Ala' (cavalry unit) of the Roman army was stationed here to oversee vital trade routes connecting the Danube frontier to the Aegean coast.