The palace in the clouds that will be Millennium Tower’s top-floor penthouse wasn’t always meant to be quite so absurdly lavish. This single unit, once complete, will span the entire 60th floor – all 12,846 square feet – of Downtown Boston’s 685-foot-tall, glass-windowed residential skyscraper. It will offer 360-degree views of the city, from 625 feet above the world. And it’s up for grabs now, for a cool $37.5 million.

Turns out, this wasn’t always the plan. The tower’s developer, Millennium Partners, actually wanted two penthouses up there. “The two units on the top floor were combined to create one penthouse,” a Millennium Tower spokesperson told BostInno in an email Tuesday afternoon.

It’s unclear when, exactly, the decision was made to pull the trigger on this planned conversion. All the spokesperson was able to tell us was that the call was made before the penthouse was listed on the market almost two weeks ago. It’s also unclear how many square feet each separate penthouse would have been, respectively, had they not been morphed into one. (Assuming each would have been split evenly, the 60th floor would have featured two 6,423-square-foot penthouses.)

So Handel Architects – the firm respsonsible for designing Millennium Tower – needs to update its website. As of this afternoon, the firm’s website still reads as follows: “The slender tower will house 442 condominiums, including 18 penthouse units.”

But, by merging two top-floor units into one, the grand total of Millennium Tower penthouses now stands at 17. That’s what Curbed, the Boston Herald, and the Boston Globe have reported.

Our Millennium Partners’s contact confirmed, 17 is the accurate number of penthouses. We also reached out via email to Handel Architects, but have yet to receive a response.

The question now is: Why decide to combined the penthouses into one?

Purely speculating, it appears one headline-grabbing $37.5 million penthouse on the top-floor of one of Boston’s tallest buildings – one that is set to redefine the entire skyline while simultaneously putting Downtown Crossing on The Map – is a bold marketing tactic. It also might turn out to be a serious moneymaker.

Three of Millennium Tower’s 17 penthouses have already been sold for over $9 million a pop. The square-footages of these 17 units, Curbed earlier reported, will range from 3,328 to nearly 13,000, the “cheapest” of which has an asking price of $7.6 million. So if you’re the developer, and you believe you can, hypothetically speaking, sell a 3,300-square-foot penthouse for $7.6 million, or one that’s 6,600 square feet for, say, $15 million – suddenly, 12,846 square feet for $37.5 million doesn’t seem that ridiculous.