Exceptionally the later fort is the only example in north-west Britain of a 4th-century type, with massive curtain-wall and projecting bastions typical of the Saxon Shore or in Wales.
The extension of this technique as far north as Lancaster shows that the coast between Cumberland and North Wales was not left defenceless after the attacks on the west coast and the disaster in the Carausian Revolt of AD 296, following on from those under Albinus in AD 197.
Lancaster is a constituent settlement of the wider City of Lancaster, a local government district which has a population of 138,375 and encompasses several outlying settlements, including neighbouring Morecambe.
Long existing as a commercial, cultural and educational centre, Lancaster is the settlement that gives Lancashire its name.
The fort underwent a few more extensions, and at its largest area it was 9–10 acres (4–4 ha).
Little is known about Lancaster between the end of Roman rule in Britain in the early 5th century and the Norman Conquest in the late 11th century.
Morecambe, Glasson Dock and Sunderland Point served as Lancaster's port for brief periods. In recent years, a high technology sector has emerged, as a result of Information Technology and Communications companies investing in the city.
Lancaster also figured prominently in the suppression of Catholicism during the reformation with the execution of at least eleven Catholic priests.
A memorial to the Lancaster Martyrs is located close to the city centre.
This erupted into a civil war over rival claims to the throne during the Wars of the Roses.
In more recent times, the term "Wars of the Roses" has been applied to rivalry in sports between teams representing Lancashire and Yorkshire, not just the cities of Lancaster and York.