It was looted by Vikings (possibly [Earl Rognvald]?) in c. 12th century AD, who left, in their passing, a series of runic graffiti on the central supporting stones of the chamber while they sheltered.
The corbelled roof was shattered in 1861 by overenthusiastic "archaeologists". Luckily, they did relatively little structural damage and the site still represents a standard of exacting design and construction not found anywhere else in Britain.