A stately Southampton mansion once owned by the nephew of industrialist Andrew Carnegie hit the market, asking $37.5 million.

The shingle-style Southampton home was built around 1898, according to owner Joanne de Guardiola, an interior designer who is married to investment banker Roberto de Guardiola of De Guardiola Advisors.

The de Guardiolas bought the home in the mid-1990s for an undisclosed sum and did an extensive renovation and restoration, she said.

The three-story house has 10 wood-burning fireplaces and 11 bedrooms, Ms. de Guardiola said, and that is after she removed several bedrooms to add more bathrooms and enlarge hallways.

The roughly 12,000-square-foot house was one of the original Southampton “summer cottages” at a time when their wealthy owners needed plenty of bedrooms for guests and staff, according to Sally Spanburgh. On roughly 4.6 acres on Coopers Neck Lane, the house is walking distance to the ocean, said listing agent Molly Ferrer of Sotheby’s International Realty.