See King's Watch bridge image for example.
When under bridges the player may attack and kill creatures with ranged attacks. I don't consider using Fire Storm in this manner an exploit since the spell sensically rains down from the sky; however, at certain angles (such as the angle shown) the player can cast ranged directional spells (e.g., Flare) on creatures.
The bridge shown in the screenshot is also unbounded. That is, the player may move his character through the support columns underneath the bridge deck.
A
