Blatobulgium, also known as Birrens, stands out as the most revealing Roman site in southwest Scotland. It’s the only major fort in the area with even faint but visible remains, and the only one still known by its original name. As an outpost of Hadrian’s Wall, it lay 14 Roman miles beyond Netherby (Castra Exploratorum) in Cumbria. The road passing through Birrens served as the main western route into Scotland.