Where is the location of AjaxControlToolKit.dll?

I migrated lots of old folders from an old PC to this new PC which I hae just installed VS 2012.  The migration also included lots of VS 2010 project, some of which were using the AjaxControlToolkit.  I had rebult some of these projects in VS 2012.

Now, in VIS 2012 I used NuGet and it shows AjaxControlToolkit not installed.  So I used it to install the latest AjaxControlToolkit version 4.1.60919 Last Published 1/6/2013.  There was no errors, and it is now shown under the Installed packages section.

I went to a VS project and Add References, but I can't see the AjaxControlToolkit.  May I know where the latest installed dll can be found.

Thanks.