A painting by Juan José Cambre presides over one end of the gallerylike entrance hall and reception space created by Stephania Kallos and Abigail Turin of Kallos Turin for a historic townhouse in Buenos Aires. The duo, who worked with the local firm Mercer Seward Arquitectos, outfitted the room with a Rosso Levanto marble floor and an Apparatus chandelier, as well as a trio of collectible design pieces: a cabinet and inlaid table by Studio Job and a Bart van Heesch copper bicycle—all from Chamber Gallery.

Kallos and Turin created adaptable seating areas in the narrow living room, anchored in the center by a B&B Italia sofa, vintage Vladimir Kagan glass-top tables, and a sheepskin-upholstered Viggo Boesen lounge chair made by &Tradition. The artwork over the sofa is by Julio Le Parc. At the room’s far end, Gio Ponti armchairs by Molteni&C face the custom-designed black-iron fireplace, joined by a vintage floor lamp and a Pierre Guariche nesting table, which is from the 1950s, as is the mirror above.

The townhouse’s street-facing façade.

An Apparatus fixture descends over the steel table and velvet-clad B&B Italia chairs in the dining room, where Kallos and Turin designed the long, black-stained oak sideboard. The walls are Venetian stucco, the curtains are a Pierre Frey linen, and the artwork is by Pablo Siquier.

In the library, a Minotti ottoman and swivel chairs are arranged around a reverse-painted glass-top table.

Kallos and Turin extended the original staircase by a floor.

In the top-floor landing area, the firm paired a Friends & Founders table with Hans Wegner chairs for Carl Hansen & Søn.

The garden’s outdoor grill is covered in tiles by Noi Estudio.

The back garden features plantings by landscape designer María Mulieri along a pool and a concrete-slab chaise with Paola Lenti cushions devised by Kallos and Turin.

Marble slabs from the 1940s line the primary bath, where the mirror, Corian-top oak vanity, stool, and storage unit were all designed by Kallos Turin; the Murano chandelier is a family heirloom.

In the primary bedroom, a Lambert & Fils light fixture overlooks the bed with a custom linen coverlet and a channel-tufted leather headboard by Kallos and Turin, who also designed the red-lacquer nightstands; Arthur Rackham illustrations hang above an Antonio Citterio sofa for Flexform and a custom-made table with a Spinneybeck leather top.