I have once again been musing on exactly how you'd structure a farm in a world of wandering monsters.
Estimates from Stack Exchange et c. suggested a bailey of about 100 people might survive with farmland of about 1.2 miles diameter, if the land is good.
With a little empty space from the forest around the edge (to keep a little distance from wandering monsters), we're at about 1.4 miles diameter.
...and may as well do the same for the brochs ('watchtowers').