Here is the situation

Old House , built in 1800's. Plank wall construction. Back part of the house is newer. Figure somewhere in 1920's the back half was put in. The back part of the house , is where the access to the Attic is located. BUT!! when you get into the Attic, you can clearly see the wall of the old section of the house, where it meets the newer section. I know there is Attic space in the old section of the house. The problem is, when they built the new part , they never cut a door opening, to get into the old Attic section.

Have no idea what that old Attic looks like. Should I cut an opening to check it out, or should I just leave it closed off?