There are several ways to get the path to the running assembly in c#.
I used to do something like
However when running unit tests etc this would cause pain and some old dirty solutions included injecting a hardcoded path for testing.
I recently found a much better way to do this when googling around on the Internet:
Uri uri = new Uri(System.Reflection.Assembly.GetExecutingAssembly().CodeBase);
String path = System.IO.Path.GetDirectoryName(uri.LocalPath);
I can´t remember where I found but now it is here anyway