Map the daylight
Mark window orientation, room depth, internal courtyards and where daylight falls away. Place frequently occupied rooms nearer the better light and utility functions where daylight matters less. This is not a universal rule: check it against ventilation and actual measurements.
Keep what gives the apartment character
Record doors, mouldings, floors and openings before demolition. A new lighting plan can combine retained details, reflective surfaces and layered artificial light, but moving walls or wet rooms depends on structure, risers and building rules. Verify these constraints before visualisation.
Improve light without erasing the historic plan
Not every long corridor needs removing. Sometimes it preserves the logic of principal rooms, while a changed room use, translucent partition or layered artificial lighting solves the problem. Compare alternatives with real furniture dimensions and window positions. List features to keep; assess structure and any heritage controls separately before proposing demolition. Better light should not mean losing what makes the apartment valuable.