High above the rooftops of Plateau-Mont-Royal, where wrought-iron staircases spiral past century-old brick and small cafés spill onto the sidewalk, a penthouse on Des Pins recently reached a turning point. Its owners' children, now mostly grown and gone, had left behind a home too spacious for its old rhythms yet far too full of memory to hand over to someone else. The question the owners faced was a familiar one for families at this stage of life: let go, or start again.