intranet has department subsites (HR,IT,sales,..). i break inheritance at each subiste and grant access to (HR group to HR site, IT group to IT site,.,.) when I add "NT AUTHORITY\authenticated users" to "intranet visitors" group at top-level site, users can see the link of the other departments with it's contents. However, I want all users to see the links for other departments (HR,IT,..) without been able to see contents (doc libraries& subsites) in other departments.
If you want the navigation to display without regard for security, then you will need to maintain the navigation manually instead of relying on the automatic "Show sites" capabilities.
However, I would suggest that links to site for which you do not have permission be hidden. This will reduce the number of times users will get the Access Denied page.