To find out what it is right now (rather than at build time, where it may be different depending on what is going on):
- right click on your project in the Solution Explorer, select Properties
- select the Build Events tab
- click the Edit pre-build or Edit post-build button, either is fine
- in the window that pops up, click the Macros button
- scroll down the list till you find
ProjectDir, in the next pane is its actual value