Ticket on project close ( or archived )

If you want to have visibility to project item, you'll see it in the Gantt...
One thing is that you can "collapse" the project so that only one line is visible.

Now, there is one extra possibility : user Administrative project type.
Projects of this type are not displayed in the Gantt.
But on the other side, every one views activities of this kind of project.
Have a look at it in the "Project type" description in the manual.