It needs interior and exterior paint, new fixtures and appliances along with some new shelving and dry wall, and of course some yard work.

@Jaron Walling @Brandon Frulla thank you both!

I have a Wall Street background and now own my own pest control company since 2011.

Having a shared wall is much better than having a shared ceiling/floor.As to the building's age, 100 years old is not immediately a bad sign because people update properties as they hold onto them throughout the years.

The foundation wall of the home was in between it and the actual house minus the doorway.

No visible mold on walls.  

This water line travels down a hill and under a retaining wall.

Sounds like you we're talking to a brick wall at B of A. 

If they leave windows open or back entrances unlocked, thermostats turned way up when testing the heat, Fridges/freezers not closed all the way, Bring in 4 kids who are running around and knocking holes in walls and tripping down steps (that they later blame on a piece of pulled up carpet) it all falls on your dime. 

@Joshua D.Make sure you check behind the walls for bodies.