Commonwealth Avenue duplex asking $5.8M includes direct-elevator access

Unit 3-4 at 54 Commonwealth Avenue in Back Bay runs the length of that building’s fourth and fifth floors, giving it a single-family look.

The cleanly contemporary duplex’s sheer size helps that look along: Eight rooms, including the potential for four bedrooms; 3,919 square feet; a media room; double doors onto faux balconies; and direct-elevator access.

Three parking spaces also come with, including two garaged.

The whole shebang is on sale through the Charles Realty for $5,775,000. Mind-bending as that sum might be, it probably does not place Unit 3-4 among the 25 most expensive listings in Boston.

It’s been that kind of summer.

• Boston’s 25 most expensive homes for sale, mapped [Curbed Boston]