This little lump is the site of an ancient broch of which scant evidence remains. The lump itself may have been created by the people who built the broch, or as a result of the broch's demolition - or it may be a natural feature that was adapted by the broch-builders - you'll need an archaeologist to give you better information I'm afraid.
Uploaded to Geograph by Rob Farrow on 31 August 2011
Photo © Rob Farrow, 31 August 2011. Licensed for reuse under this Creative Commons licence