Lancaster's history can be traced back at least to Roman Times. The romans built a fort here on the site of the current castle, remains of a Roman Bath House can be seen just north of the Priory Church. By the fourth century the garrison cavalry unit had been withdrawn and replaced by a smaller infantry batallion, which meant that to make the fort defensible it had to be reduced in size. During this operation the constructors levelled the site then dug-out the defensive ditch for the new fort, cutting through the ruins of the old bath-house as they did so.
|Several Roman roads radiated out from the fort, the road via Caton and Hornby to the fort at Low Burrow Bridge todays A683 being the main road north. The main road south went near to the coast passing Conder Green, Covckerham then south to Preston following the route of the A588 up to Cockerham then the B5272 before linking up with the A6 just west of Garstang.The Roman milestone found four miles to the north-east of Lancaster on the road to Kirkby Lonsdale which suggests that the Roman name for Lancaster began with the letter L; perhaps Lunium? The modern name first appears in the Domesday Book of AD1086 where it appears Loncastre, a compound of a Celtic river-name and Old English cæster or 'old Roman fort'. The full meaning of the modern name then, is 'the Roman fort on the River Lune'. It is very likely that the Latin name has the same derivation.|