The Wild is not populated with buildings for your convenience. The true wilderness traveler is fully capable of erecting, digging, or building his own shelter in a multitude of environments.
Knots
You know your way around a rope, and that includes the bowline, the clove hitch, the sheet bend, the reef knot, and the timer hitch. These are the foundation of wilderness building. Intellect
Lashing
You learned those knots for something, right? Lashing allows you to bind sticks, spars, and logs together- as long as you have quality rope. Diagonal, round, sheer, and square, you know them all.
Basic Structures
The A-Frame, the Trestle, and the Tripod are building blocks for more complicated structures.
Bench
For resting your arse.
Fence
It'll probably keep cattle and wolves out, right? Especially if you have wood to spare.
Raft
Getting across a river doesn't have to be that hard.
Table
To put things on.
Chair
Like the bench, except you use more raw materials. Congratulations.
Simple Bridge
Nothing more than some rope and a long piece of wood, really. For one man.
Ropeslider
Get from a higher point to a lower point. Make sure that rope is strong.
You'll probably need help erecting the structures below.
Tower
A basic lookout tower.
Bridge
An actual bridge, which requires a lot more wood.
Catapult
A crude catapult designed to fling stones.
Trebuchet
This is not the trebuchet that a siege engineer would construct, but a much simpler, less accurate, less powerful likeness.