In the old days, things were different. How different depends on how old the days are. It's hard to anticipate every issue you might encounter in an old project. The first question is, what do you need from the project? Do you need drawings, a detail, or are we actually resuming work on the project?
If you just need to print a set, visit the plot or PDF archive of the project. If you're using plot files, they should be sent out for best results.
If you need a detail: Save the detail as a module before bringing it into a current project. If obsolete objects are used in the detail, I recommend replacing them with current versions. Keeping obsolete libraries loaded invites errors. And old objects are lame.
If you are resuming a project that has been on hold: Open the project in the current AC version. Don't work in old versions. It's always worth it make the adjustments to be up to date. This is true for all versions through AC9. Migrating a project from to 10 is much, much more involved. It should not be attempted for any project that is in CDs.
If you are doing addition/renovation work to one of our past projects: Read This.