Crawford Notch is a wild, rugged mountain valley that angles right through the heart of the White Mountains. There's a surplus of legend and history here. For years after its discovery by European settlers in 1771, this was an impenetrable wilderness -- and a literal barrier to commerce, because it blocked trade between the upper Connecticut River Valley and the busy harbors in Portland and Portsmouth. Eventually some plucky bunch got through the pass, and it developed into an important route.
Nathaniel Hawthorne immortalized the notch with a short story about a terrible real-life tragedy that struck here in 1826. One dark and stormy night (naturally), the Willey family fled their home when they heard an avalanche roaring toward the valley floor. As fate would have it, though, the avalanche divided above the house and spared the structure entirely; all seven were killed in the tumbling debris because they weren't in the house. You can still visit the site today -- watch for signs when driving through the notch.
The notch is accessible via U.S. Route 302, which is wide and speedy on its lower sections, then becomes steeper as it approaches the narrow defile of the notch itself. Modern engineering has taken most of the kinks out of the road, so you need to remind yourself to stop from time to time and enjoy the panoramas. The views up the cliffs from the road can be spectacular on a clear day.
By the way, don't get confused by directions referring to the towns of Twin Mountain and Bretton Woods. These are the same village; it has two different names.