Looking for a field in Projects to record data in a date format.

We are trying to find an additional place to record a date (not transaction duration type date) on a project.  We were thinking of adding an additional classification field to store this date, but so far we have not been able to figure out a way to format the field in a date format, it seems to only allow text data.  Does anyone have any suggestions on where this could be stored or how to format a new Classification field?  Any help would be greatly appreciated.