It's perched on a hillock that dominates the surrounding country. On one side is the river and the crossing, which would have been very exposed to longbow and fire. On the other side, the land dips down before rising again. Imagine charging down that hill and then seeing the wall of the Great Hall towering above you. It would make anyone pause and wonder what they were doing there. But it's also so compact - Chepstow doesn't even have a single complete curtain wall. Yet with masterful planning, anything short of a massive army (or cannon) couldn't get in. English (or should I say French?) engineering at its best!