Sostra castrum

Sostra is an ancient Roman fort and settlement located near the village of Lomets in central Bulgaria. Originally established as a mansio or roadside station around 100 AD, the site was developed into a substantial military castrum in 147 AD under the orders of Emperor Antoninus Pius. Strategically positioned along the Via Traiana, this vital artery connected the major cities of Philippopolis and Diocletianopolis with key outposts on the Danube frontier, such as Ulpia Oescus and Novae, via the Troyan Pass. The fort served as a critical logistical hub during Trajan's Dacian Wars and later functioned as a primary defense and supply line for the Roman province of Thrace.

The garrison stationed at Sostra included the Cohors II Mattiacorum milliaria, a unit comprising approximately one thousand soldiers. Over time, a civilian settlement known as a vicus grew around the military installations to the east and west, eventually evolving into a thriving town. Archaeological excavations have revealed impressive remains, including parts of the original fortification walls and evidence of high-quality living standards, such as an ancient heating system for a luxury bath complex. These findings highlight the site's importance not just as a military stronghold, but as a prosperous community within the Roman network.

Today, the ruins of Sostra have been partially restored, allowing visitors to observe the layout of the historic fort and road. While the site itself stands as a testament to Roman engineering and military organization, many artifacts unearthed during excavations are housed in the local museum in Troyan. The preservation of Sostra offers valuable insights into the daily life of Roman soldiers and civilians in the Balkans during the second through fifth centuries, marking it as a significant historical landmark in the region.