Their primary base is an underground mobile fort known only as the mothership.

They were confined in an old fort known as, "Castle William."

This is one of the forts known as the 'Famous 5'.

Today, many scholars believe it is more likely to be the fort known as Magis.

To the west is the remains of a Roman fort known as Habitancum.

There are over 2000 of these forts known in Britain alone.

It was the site of a Roman fort known as Venonis.

During 1890 work began on an eighth fort, known as Linkuva; new construction techniques were introduced, particularly reinforced concrete.

They even built a fort known as the Robbers' Roost.

The fort known for its architectural elegance was the location of several battles in the past.