They comprise a series of forts, strong points and ditches, designed to protect the country from invasion.

They were created to augment the existing defences and protect the key port of Dover from both seaward and landward attack.

The site then held male adult detainees aged 18 and over who were appealing for asylum or had failed in seeking it.

The centre offered residential space with integral sanitation as well as resources such as televisions and telephones.

It provided shared resources including gym, a library, church, mosques, multi-faith rooms, shops, laundry facilities, and a healthcare unit.