Dros Delnoch is made of six concentric walls and a keep.

They were built using two concentric, dry-stone walls to create a hollow tower.

Sreekovil has an outer perimeter of 160 feet and has three concentric walls.

It had three concentric defensive walls surrounding the inner, topmost ring.

They pass up through the 7 concentric walls and gates to the White Tower.

And the tower, like her own picture of concentric walls, would be a metaphor for mind.

Four concentric walls ringed the base and the lower portion of the slope.

The complex is protected by three concentric walls which define the main areas of the 'town'.

He pointed across the cavernous space, where a second series of concentric walls were going up.

The layout of the site is surrounded by two concentric walls which served as defense against attack.