Maps of each floor of the Barco Law Library, as well as a detailed map of the materials in the Zittrain Reference Collection on the 4th floor, are available for download on the "Downloads" in the lower right-hand menu on this page.
As a general guide:
The Third Floor materials include the Treatise Collection and the Foreign and International Law Collection.
The Fourth Floor is the Main Floor and materials include primary law materials and Pennsylvania Law.
The Fifth Floor materials include journals and primary materials.