This fourth-floor loft in a classic cast-iron building in the heart of Soho has great bones.

Such great ones that the seller hired architect Andrew Berman, known for his designs at such spots including MoMA PS1 in Queens, to oversee a gut renovation.

The 2,800-square-foot unit at 100 Grand St. — in the original Cast Iron District between Mercer and Greene streets — is now on the market for $6 million.

The full-floor residence comes with two bedrooms, two baths and a $3,300 monthly maintenance fee. Interior designs are by Justin Charette.

The seller bought the home for $3.72 million in 2013, and renovated it in 2014.

Details include exposed brick, wood columns, wide-plank white oak hardwood floors, tin-panel ceilings and oversize windows.

The spread is anchored by a 1,300-square-foot great room. There’s also an open chef’s kitchen and hallways that lead to the bedroom suites at opposite ends of the home.

The six-story building comes with keyed elevator access. It was built in 1910.

The listing brokers are Amy Mendizabal and Calli Sarkesh of Compass.