1. Stair inspired by the furniture of Jean Prouve. Antique oak treads.

2. A fifteen-foot 60s glass hanging by Michael Higgins connects two floors.

3. Dining Room. Eero Saarinen chairs (60s) in Alexander Girard houndstooth, George Nakashima table (70s), Pierre Guariche ceiling light (50s), and Robert Rauschenberg collage.

4. Living room. Andy Warhol Marilyn lithograph, Laurie Simmons photograph, Tapio Wirkkala side table (60s), Edward Wormley coffee table (60s), Yngve Ekstrom chair (60s).

5. Living room looking northeast. Charlotte Perriand "Mexique" shelves (40s), Poul Kaerholm leather chairs (50s), Florence Knoll sofa (50s), Josef Albers prints.

6. Kitchen. Glass-fronted legal bookcase as upper cabinets and poured porcelain counters with stainless steel edges. Custom lower cabinets have built-in rail for ladder to slide.

7. Study. George Nelson wall unit (70s), Alexander Girard chair (60s), Eero Saarinen "Womb" chair (60s), Tapio Wirkkala standing lamp (60s), Pietro Fornasetti side table (60s).

8. Study and Guest Room. Florence Knoll club chairs (50s), Anglepoise lamp (60s), George Nelson side tables (50s), Nessen lamp (50s), "Wave Wall" hanging.

10. Living room detail. Charlotte Perriand scone (60s), Pietro Fornasetti lamp (50s), Cabat Feelies (50s), Donald Baechler collage, Nathan Carter painting, etching after Raphael.

10. Living room detail. Charlotte Perriand scone (60s), Pietro Fornasetti lamp (50s), Cabat Feelies (50s), Donald Baechler collage, Nathan Carter painting, etching after Raphael.

11. Bedroom. George Nelson cabinets (60s). Anglepoise lamp.

12. Plans before. Two identical one-bedroom apartments.

13. Plans. New stair. Kitchen in former foyer of 10th floor apartment. Study and kitchen opened up to dining room. Living room overlooks new stair.

14. Section through two-story space created for new stair. Living room balcony looks onto new stair. Kitchen on and storage on lower level.