Cannot find it anywhere, I've been hunting it down for an hour now.. Looking at it in this map on the Web and just can't find it on my map in the game anywhere near the other landmarks..

You mean Hags End? Even though it is an exterior cell, you can only reach it through Deepwood Redoubt

http://www.uesp.net/wiki/Skyrim:Hag%27s_End

There are a couple places like this in the game.