Sostra Roman Fortress stands near the village of Lomets in the Troyan region as the best-preserved Roman military post in Bulgaria and a unique architectural monument within the entire Roman Empire. Constructed around 147 AD under Emperor Antoninus Pius, this diamond-shaped stronghold measured 130 by 130 meters and housed a military cohort of 1,000 soldiers. Positioned strategically along the vital ancient road connecting Exos to Philipopolis (modern-day Plovdiv), linking the Roman provinces of Lower Moesia and Thracia, the fortress controlled important trade routes. Archaeological excavations uncovered antique pottery, jewelry, and artifacts now displayed in Troyan's Historical-Craft Museum and Bulgaria's National Museum of History, providing evidence of its sophisticated Roman occupation before its destruction by the Goths in the 4th century and the Huns at the 6th century's end.
