Titan Wall

Standing twenty feet high, running from the mountains to the sea, the Titan Wall stands as a solid border between the Savage Lands and the City-States Region. The origins of the wall are unknown to those living today, but the weathered black glass of the wall is the only visible monument to the fallen Giants' civilization.

(Ancient) History

The origins of the Titan Wall date to the civilization of the Giants and the Age of Titans. The wall was formed through the powerful ordering magics that the giants had used to give form the world out of elemental chaos. In the case of the wall, the giants forced magma from an ancient volcano into a channel running along a border between their domain and a land that was still swarming with wild elementals. After the wall of magma cooled, the earth around the channel was pushed away, and the wall stood - shining and faceted, reflecting the red light of the wild land.

Today

Eventually the giants' civilization would fall thanks to a cataclysmic volcanic eruption. Millennia later, as the City-States Region began to be populated after the Dragonscourge, the wall formed a natural barrier. After the several thousand years that had passed since its formation, the wall was now weathered and cracked on its surface but still solid and impassible. Thanks to the wall serving as a border, after the Lasair Compact was created, the Mages also negotiated a treaty between the Orcs and Humans setting the Wall as a hard border between the two regions.

The Wall

Physically, the wall is solid obsidian, running roughly east-west in a perfectly straight line between the Northwall Mountains and the western sea. The wall seems to emerge from the mountains as if it was covered by the mountains after it was created (which is not far from the truth). At the sea, the wall simply ends at the cliffs that fall into the sea; its end jagged and hanging slightly over the cliffs as they've slowly eroded away.
The wall stands twenty feet in height; fifteen feet across. The surface is weathered and cracked, but still completely solid under the surface. It reflects light much as worn black glass, and can be extremely warm on sunny days. The top is flat, with no crenellations, though over the years the Mercenary Guild has built wooden fortifications atop the wall at several points. As the wall has no openings for crossing (or climbing) the Guild has similarly built steps up to the top at various locations and rope ladders are generally used should anybody need to go down to or come up from the north face. For the Orcs' part, they don't consider the need for climbing the wall but if they find need their tribes often carry climbing hooks.
Part of what the Mercenary Guild guards against from the wall isn't the Orcs but rather the Ratlings. The ratfolk will periodically raid the wall, with clever extending ladders, or by burrowing underneath with mechanical diggers. The Guild patrols the wall with small squads marching between outposts across the top, based out of a number of fortified camps on the south side of the wall. Guildhall, the Guild's headquarters fortification, is based at the eastern end of the wall, next to the mountains.

Who Knows This?

An Intelligence (History) skill check will bring to mind the following depending on the character's roll:

• DC 5 (Common knowledge):
  There's a big wall to the north of the City-States Region called "The Titan Wall"
• DC 10 (Could hear it from travelers):
  The wall is guarded by the Mercenary Guild and looks like solid black glass
• DC 15 (Education covered it):
  The wall is perfectly straight, and has stood since before the Dragonscourge; the "glass" is very likely formed from cooled volcanic lava
• DC 20 (Learned Historian):
  The wall predates even the Imperial Era
• DC 25 (Subject Matter Expert):
  The orcs retreated to behind the wall with the arrival of Imperial explorers and the first human settlements in what became the City-States region
• DC 30 (Directly Acquired Knowledge):
  the wall was created by a race of giants that existed several millennia ago and went extinct through some unknown disaster

Notes: Characters who have personally visited the wall will automatically know the first two items from experience. Characters who have served in the Guild will know the third (and will willingly share if asked).