Geoff shot to fame with an analysis that showed Hadrian's Wall was originally timber.
As part of a documentary, he's recently posted this article about earthworks alongside Hadrian's Wall.
A lot of his other work is on prehistoric structures, such as roundhouses and forts.
The most amazing thing about his archaeology reports is that they are actually well-written, highly readable if you can cope with the minute detail, and sprinkled with fun phrases. I wish all academics and business people wrote as well as him. I particularly like his view that the proper study of mankind is postholes.