This small condominium in Midtown’s restored Biltmore is a tranquil retreat for hard working professionals.  Designed to accommodate their art collection, at night the place becomes a place of shadowy light.  Natural materials make up the warm palette:  Bamboo floors, red oak doors and cabinetry, slate bath enclosure, and honed black concrete countertops.   Backlit panels of frosted glass produce a glow.  An encaustic (wax painting) by Tom Swanston floats in the bedroom ceiling.  Bathroom details include a concrete sink-bowls and river pebbles in the floor.