What do you do with your new $120 million home? Visit it on Saturdays and Sundays.

The billionaire Indian Poonawalla family last week agreed to pay that much for a former maharajah’s residence in Mumbai that most recently had been the U.S. consulate in the city. The owners of Asian’s largest maker of vaccines may use it about two days a week.

“We always visited Mumbai on the weekends,” Adar Poonawalla, chief executive of Serum Institute of India Ltd., said in an interview Wednesday in Pune where he lives, about four hours from Mumbai. “We have a lot of our horse racing in Mumbai on the weekends. It’s not going to increase my visits.”

Lincoln House, as the building has been called during its U.S. ownership, sits on a two-acre plot on the shores of the Arabian Sea in the Breach Candy neighborhood of south Mumbai. The 8 billion rupee ($120 million) price, which includes taxes and other fees, is a record for a residential sale in the city, according to local media reports including Livemint.com.

Because of its heritage, Lincoln House has landmark status and can’t be fundamentally altered, but that didn’t deter Poonawalla.

“We hope to open up the rooms and -- because at the moment it is designed as a consulate -- there are a lot of security rooms and waiting rooms and all that,” said Poonawalla, 34. “We’ll have to demolish what we can internally. We will have to do it up a little bit, with the permission of the government.”

Maharajah of Wankaner

He hopes to improve the appearance of the facade, “but we can’t demolish it. We might build another floor, but that’s all dependent on the permissions.”

The property was erected in 1938 by the Maharajah of Wankaner and sold to the U.S. government in 1957 on a 999-year lease. It served as the U.S. consulate for more than half a century, until surging demand for visas led the U.S. to shift activities to a 10-acre plot in the Bandra-Kurla business district of northern Mumbai a year ago.

Poonawalla said the decision to buy Lincoln House wasn’t a business one.