User blog comment:Essie Essex/Interactive Dunwall Map/@comment-27004218-20151222134035/@comment-16533050-20151223210406

TL/DR- typical Geist response

Living near the Mississippi River myself, and seeing how the Wrenhaven itself seems to be based off of the Thames, I can say (with more than a little assurance) that the part of the Wrenhaven represented is no way indicative of the whole.

Simply because something is 'upriver' of the Wrenhaven doesn't mean it is immediately to the west. The River may jut or turn, have a strong but oddly shaped natural bend in it that drives it strongly Northward or Southward.

Near the far western side of the map, the river does indeed seem to take a severe south-western turn. Perhaps the river continues on like this, which would make Brigmore Manor south, by southwest of the current area.

Oddly though, if the Wrenhaven continued on this way, there is a good chance that southern Dunwall may be its own island, as the Capital of the Empire is located on the southeastern part of the Island of Gristol.

We don't even know how long the Wrenhaven is. The Thames River is 215 mi. The Mississippi is 2320 mi. Therefore the part shown on the map is but a portion. Especially when viewed on the map of Gristol.

Also, we don't even know which side of the river on which Brigmore Manor sits. That, too, would influence its positioning on the map.