The Thandol Span was one of the greatest engineering projects ever completed by the Dwarves. Built on the site of the original three land bridges, two stone bridges spanned the cliffs. It is located in an area once known as the Thandol Valley.
This massive, dwarf-made bridge stretches across the natural canal that separates Lordaeron from Khaz Modan. The Thandol Span is solid and large, a blocky stone edifice with numerous thick support columns plunging into the water. Scourge forces damaged the bridge in the Third War. Great sections broke off and now lie beneath the waves, some visible at low tides. Nevertheless the Thandol Span is still easily navigable and serves as the only land route between Lordaeron and the southern continents.
The bridges were capable of supporting the weight of entire armies, and served as the main route of trade between the dwarves and Humans. The mighty bridges recently suffered heavy damage due to a Dark Iron attack planned by Kam Deepfury and Balgaras the Foul. One of the two bridges has now been all but destroyed, and dwarven forces are fighting fiercely to defend the last remaining bridge and retake the nearby town of Dun Modr. During this assault many dwarves died, including Sully Balloo, Ebenezer Rustlocke, and the brother of Longbraid the Grim.
(As seen on the WoWWiki.)