the earth hall

 The earth hall

 Inside a barrow, there is a cavern, or a great hall, 

in which sleeps a knight until he is needed to protect his people, 

or else a dragon, curled up and waiting to arise and terrorise

 the community, or the spirits of the dead, which return

 like vampires to inflict revenge on the living.

Obviously if it is a tomb, then it would stand to reason that 

something incredibly precious is hidden there.

The tale of Grendel and Beowulf's battle with the spirit, and its mother,

 of course is in line with these stories. 

Exactly what kind of spirit the Grendels were is hard to define,

 and they are often interpreted as being dragons, 

but they seem bloodthirsty.

Iron Age hill forts are often shaped with dragon-like rings 

or embankments surrounding them, which may have something 

to do with why serpentine  monstrous worms are supposed to live there.

Such serpents are alleged to have driven away treasure seekers,

for instance, at Cissbury Ring.

There is alleged to be a tunnel leading from Offington Hall (demolished in 1960s)

to Cissbury,  and in the nineteenth century, 

 a blocked tunnel entrance was found behind pannelling in its library,

and explorers trying to open the tunnel,(about 2 miles)

were chased away by ghostly serpents.

As serpents are  tunnel dweller, of course, 

The manorial hall joining to the earthly hall, 

The corporeal power to the spiritual in the community.