Three early Neolithic houses were recently unearthed in Berkshire, England. Above are field photos; click on this for more detail, and you can see that the foundations at left and top right consist of a single, narrow, continuous trench. The archaeologists have dug sections of the trench to make it stand out better, but the trench, marked by the dark stain, is continuous.
The folks at Wessex Archaeology interpret this as above, with walls made of standing boards set in the narrow trench. If so, these people put a whole lot of work into splitting logs with stone tools. The house at lower right was supported by posts, with walls possibly of wattle and daub.