1. I prioritise on storage ideas. Decor ideas would be grateful too. The Hallway is approx 3 and a half feet wide, 15' long and 10' tall. I would still need space to move freely without banging my leg or toe!
2. One side is a newly made structure with TMT and cement. While the other side is old structure of sandstone slabs and 9 inch walls.
3. The new wall is plain 4 inch. One door at the end, opposite of which is a vent in the old wall. The old wall also has a mid double door and a window plus vent beside.
4. At the other end there's an interior stairway in the old structure with double door.

Too many points, I agree. Pictures would help. I have added a rough (not to scale) figure for better understanding.

I'd be very thankful. Please suggest.