Blatobulgium (or Birrens) has proved itself the most informative of all Roman sites in south-west Scotland. It is the only major fort in the region where there are unmistakeable, if slight, visible, remains, and it is the only one known to us by its original name, Blatobulgium. It was an outpost fort of Hadrian's Wall, 14 Roman miles on from Netherby (Castra Exploratorum) in Cumbria. The road through Birrens was the main western route into Scotland.