Celebrity couple John Legend and Chrissy Teigen are planning to list a pair of apartments they own in New York’s Nolita neighborhood for $18 million.

In a landmarked, 19th-century building known as the Brewster Carriage House, the two contiguous penthouses span nearly 6,200 square feet with six bedrooms, according to listing agent Noble Black of Douglas Elliman.

The couple purchased one of the units for $9.02 million in 2018, and the other for $7.7 million in 2020, records show.

The musician and Ms. Teigen, a 36-year-old model and social-media celebrity, used one of the units as a pied-à-terre. They had plans to combine the units into one penthouse across two floors, but never did, Mr. Legend said.

“We’ve realized that because of work and everything, we’re really mostly going to be in Los Angeles, so we’re going to focus our home-building energy and renovation energy on what we’re doing in L.A.,” said Mr. Legend, 43.

They are planning to purchase something in New York that doesn’t require any work, he said, adding: “We love being there. But we’re just not there enough to justify putting in the time and energy to combine apartments.”