The picture above is me climbing into Tower Gap. Tower Gap is the hardest part of the climb (Tower Ridge). Mainly because of the 3000ft drop down either side of you and the fact that it is no wider than a car!
This shows a clear anitation of the North Face on Ben Nevis. Tower Ridge is the climb I did.
The cut out of the rock, near the cenre of the image is tower gap. I hope this gives you a good insight on just how exposed and and scary it was. But apart from the scariness, it was my favourite part of the climb. It is also the most famous part.