Tucked on a tranquil tree-lined st where South End & Back Bay meet, this unique home is from the outside a traditional Federal-style brick rowhouse. Inside it is a re-engineered marvel. 4 open levels of living centered around a graceful, steel-framed staircase. Steel & brick support the structure so no interior walls are needed, leaving rooms to be totally open or partitions where desired to be made of translucent materials not drywall. A pyramid skylight carries sunlight from the roof. Green is in view from every window on all sides. Private outdoor spaces: a Zen garden & skyline-view roofdeck. Garden & parlor comprise the main living area: foyer, 2 living rms, dining rm, kitchen & 1/2 bath. 2nd floor w/ guest bedrm, full bath, & 2nd bed/library w/ hidden Murphy Bed. Top floor master suite w/ W/D. Ample concealed storage w/ closets or custom built-ins in every room. All high-end materials, Miele & SubZero, 2 zone heat/AC, gasFP, central sound & more! Garage space @ Atelier 5 min walk.