Old rooms are rarely as symmetrical as their photographs. One alcove is wider, one wall leans a little, and an outlet sits exactly where the most elegant shelf wants to end.
Measure the differences before hiding them
Get the openings measured at several heights and depths. Include skirting, cornice, outlets, and any required clearances around a fireplace or heater. The finished design must follow the appliance requirements where those apply; a balanced photograph cannot override them.
Matching lower cabinet heights and a shared finish can create order without making every shelf identical. Equally, genuinely similar openings may benefit from a simple repeated arrangement. Symmetry is an option, not a moral obligation.
Use the books you own
Lay out books, records, baskets, speakers, and the things you would rather conceal. A tall art book has a more persuasive argument than an evenly spaced shelf grid. Give each side a job, then compare how much display area the room can comfortably carry.
IKEA’s bookcase and shelving range offers examples of open and closed combinations. These are planning references, not dimensions or support specifications for custom joinery.
Review it from the sofa
Print a simple front elevation and look from the usual seating position. Try matching the cabinet line and varying the shelves above it. Our preference is a few shared lines, with the awkward dimensions absorbed where they do the least harm. Choose exact matching only when it makes both sides useful. The wall should feel settled, not caught trying to disguise itself.