Project information is stored in different places but it seems the main project information is stored in a sub-folder in the .metadata workspace folder.

The exact location is:
.metadata\.plugins\org.eclipse.core.resources\.projects\

But other project related information is stored in other locations, example:
.metadata\.plugins\org.eclipse.debug.core\.launches\
.metadata\.plugins\org.eclipse.ltk.core.refactoring\.refactorings\

Posted in Eclipse Programming by stevenmarkford