Imperial Harbour is a Empire port building in Total War: Warhammer. Whether man-made or natural, a harbour is a place for vessels to wait out Stromfel's rage.
There are many harbours in the Old World, as the nations oft use the large flowing rivers to transport goods from one place to another. Even the Empire's great inland cities have some kind of harbour for massive river barges to dock. The most famous of all harbours, perhaps, is in Barak Varr, the sea-gate of the Karaz Ankor.