Where can I find the web site ID of a project site in Project Server 2010?

Hi, I need to find the ID of the project site of a project in Project Server 2010 in order to be able to identify that web site in the Sharepoint Content DB (in the reporting DB, in Projects_View appears the URL of the project site but not its web site ID). I need to list the documents stored in the project sites of the projects contained in the Project Center inside PWA.

Thank you very much

Regards