Greymane Wall

The Greymane Wall was built after the Second War, by King Genn Greymane.

The nation of Gilneas isolated itself from the Alliance due to a dispute surrounding the internment camps for the orcs. It is a large wall with a portcullis, located at the southern edge of the Silverpine Forest (near Pyrewood Village) and the northern edge of Gilneas.

The Greymane Wall is the only evident site of Gilneas. This enormous gray wall marks the boundary between Gilneas and Lordaeron. No guards stand at its battlements or man its gates — the wall seems dead. Nevertheless, refugees from the north camp in the wall’s shadow, hoping for succor. These unfortunates never see a Gilnean and are easy prey for the worgen that occasionally stray this far south from Shadowfang Keep.

Those on the other side in Gilneas have been spared from the Plague, though the worgen curse has taken effect instead...

The wall currently marks the start of the Lands of Gilneas..

Reference: WoWWiki..