Castra ad Montanesium

Castra ad Montanesium is a Roman fortress on Kaleto Hill in Montana, northwestern Bulgaria, rising about 40 metres above the town. The site was first settled during the Chalcolithic (4th millennium BC), later becoming a fortified Thracian village with walls over 1 metre thick. Romans attracted by gold and ore deposits along the Ogosta River established a military camp that received municipal status in 160-161 AD. Gothic invasions in the mid-3rd century prompted construction of massive fortification walls with gates, towers, and basilicas. Secondary walls were added on the south and east sides during the 4th-5th centuries. The fortress was destroyed in the 6th-7th century during Avar or Slavic raids, after which Slavs built a settlement over the ruins, converting a surviving Roman barracks into a pagan sanctuary.