This programme delves into the mystery of the super fortress 'Deva' – the Brobdingnagian building that marked the edge of the Roman Empire.

For over three hundred years, the fortress was the strategic command base of ‘Valeria Victrix’, the infamous twentieth legion. This ferocious elite fighting force crushed Boudicca's bloody rebellion in c.60 AD, and later played an indispensable role in the construction of Hadrian's Wall: the 73.5 mile long stone and turf fortification which came to physically define the frontier of the Roman Empire, preventing military attack from Scotland’s contumacious tribesmen. 

The extraordinary scale of Deva has confounded experts for generations. Archaeologists and historians have consistently questioned why the largest military garrison in Western Europe was located in such a remote outpost of the Roman Empire. 

Deva’s unique architectural style, which was far removed from the building approach adopted throughout the rest of the empire, has proved equally perplexing. Furthermore, the prominence and scale of Deva has prompted questions regarding Ireland’s treatment at the hands of the Romans, and the country’s possible role in the British rebel empire which broke away from Rome's control.

This programme marks the culmination of forty years of meticulous detective work. Archaeologist-historian Mark Olly delves exhaustively into the Roman master plan, finally revealing the true significance of Deva. With input from leading academic experts Dr David Mason, Professor David Shotter, Dan Robinson and military historian Mark Corby, they scrutinise the fortress’s position at the forefront of the conquest of hostile territories at the empire’s 'final frontier': northern Britain.

Specially commissioned re-enactment sequences, newly shot material, unique archival footage and sophisticated CGI sequences bring this incredible detective story to life, unravelling a raft of new facts about Roman Britain. As a plethora of experts outline the true extent of Rome’s military ambitions in Europe, viewers will be forced to re-evaluate the final years of the Roman Empire.