Highwall

Highwall is a fortress in the Imperial Domain which spans the length of a thin gap between the Mernel Mountains and Morktan Mountains. It is the only gap between the two, and is therefore a vital artery of trade, being a major chokepoint of the Marble Road. Highwall has been fought over for centuries and has passed between various kingdoms, houses, and lords over the millennia. The fortress was constructed during the Dark Age of Man. Today it is the seat of House Aran. 

The fortress is surrounded on both sides by steep rocky cliffs, into which tunnels are carved to allow archers to sit on guard at all times. The fortress itself covers the entire pass, forcing travelers to either pass through and pay the toll to House Aran, or risk a deadly trek over the perilous mountains.