When the Romans arrived in AD 72 they built a fort in the area between Tullie House Museum and the castle, and named it Luguvalium after Lugh. The southern gateway opened onto a road leading through the gardens of Tullie House and along Blackfriar's Street to Botchergate and the route to London. Another Roman road crossed the River Eden and came up what is now Scotch Street. Carlisle later became an important frontier settlement behind Hadrian's Wall, a 78-mile long stretch of continuous wall between Wallsend and Bowness-on-Solway, completed in AD 122.
The existence of a large Roman army in Carlisle attracted trade and industries to service their needs, and a substantial vicus or civilian town developed to the south-east of the fort. The remains of shops and dwelling houses have been excavated along Blackfriar's Street and other Roman remains lie beneath the Market Hall and The Lanes shopping centre. With increasing prosperity, Luguvalium became a civitas (an important administrative and economic centre).