The surface palisade was constructed under the overseership of Sir Brenzen the Bold as a measure intended to restrict hostile access to the fortress. It's original design consisted of a large wall extending out from the fortress entrance, a trade depot designed to keep intruders out, and the barracks and archery tower. The barracks was the only normal point of entrance into the fortress, so that foes were forced to first confront the military rather than being able to sneak into the fortress unnoticed. The surface palisade has been greatly renovated since that time, although it retains much of its original purpose and form.
During the second reign of Sir Brenzen, he ordered a massive revamping of the fortress defenses following a goblin siege that killed a skilled farmer and an elite marksdwarf.
The barracks, created during the reign of Sir Brenzen, has served as the military center of the fortress ever since its construction. It provides a fairly spacious area to train in and also serves as a channel, forcing all enemies to enter the fortress through it.
Just beyond the barracks is the gatehouse. Also constructed during Sir Brenzen's overseership. It was later filled with cage traps and serves to capture anyone who gets past the outer defenses.
Beyond the gatehouse is a precarious walkway over a pit, where weapon traps wait to knock those who would test the fort's defenses to their doom. Retracting bridges extend between sieges to allow dwarves to more safely leave the fortress.
The trade depot of Demongate is placed on top of the palisade, after the original depot was sealed off. A single bridge allows the depot to be sealed during invasions. Below the depot lies the trade good storage.
While not technically part of the palisade itself, the ballista battery serves as an additional line of defense. While it is rarely used, the ballistae overlook the outer defenses and are intended to obliterate all who would approach too closely. During Sir Brenzen's second overseership, he ordered the production of additional ballista arrows, though the ballistae remained unused during the first siege during his overseership.