Ancient building in southeastern Diyarbakir province of Turkey was once used by Romans as military settlement

Zerzevan Castle, with its unique architecture and style, is regarded as one of the "best-preserved" Roman garrisons of the world, according to UNESCO. The hinterland of the castle once formed the extreme borders of the empire in the east and witnessed struggles of top-tier powers of the era in their pursuit to dominate the region in terms of economy, politics, and military.