This drawing, by a Mr. Gibb of Aberdeen, Scotland, depicts the state of Maeshowe shortly after the excavation through the roof of the structure in 1861 by the antiquarian James Farrer.
Based on Wikipedia content that has been reviewed, edited, and republished.
Original image by Mr. Gibb. Uploaded by Joshua J. Mark, published on 24 October 2012 under the following license: Creative Commons: Attribution-ShareAlike. This license lets others remix, tweak, and build upon your work even for commercial reasons, as long as they credit you and license their new creations under the identical terms.