Hi K P,
The data you are looking for lives in Tableau Server's Repository. The Repository is a PostgreSQL database that stores server data that you can connect to in order to create your own custom administrative views.
Before you can connect to it you have to enable access using one of two usernames, tableau or readonly. The readonly username has access to more tables than the tableau username but those tables may be changed without warning. You can read about the differences here: Create Custom Admin Views. To enable the usernames you will need admin access to the server so you can run the tabadmin commands as described here: Collect Data with the Tableau Server Repository.
Once you have enabled access, you can connect to the PostgreSQL database in Tableau with one of the usernames. Here you will find all the information you need on sites, workbooks and views in their relatively named tables. Each view has the workbook id that it belongs to and each workbook has the site id it belongs to. For an in-depth description of the tables and their fields you can look in the Data Dictionary. From here you should be able to create the report you need.
Let me know if you have any questions.
This is great.
Thank you Keshia