Where to place engineering dll used by website

[Torben Laursen]

Hi

My asp.net website is using a c++ dll that I have written.
But where should I place it so I don't have to hardcode the path in the c#
code?
It is used by code that is inside the App_Code folder using a number of
subfolders
I would like to be able to just write like this:

[DllImport("Calc.dll")]

Thanks, Torben