The coolest apartments are always in Paris. This one is by Monaco interior architect team Humbert & Poyet. A stunningly simple fireplace, graphic artwork, classic furnishings by the likes of Eero Saarinen, Mies van der Rohe and Serge Mouille combined with tall ceilings and to-die-for moldings make this apartment in Le Marais a total dream. (Check out another one of their projects here)