In the early 1970s, John Lennon and Yoko Ono rented a two-room apartment on the top floor of an unassuming townhouse at 105 Bank Street in New York’s West Village. In more recent years, the small apartment house has been gut renovated and fused with the neighboring townhouse at 107 Bank Street to create a colossal single-family home of nearly 13,000 square feet.

Apart from the carefully preserved facades, the award-winning firm Robert A.M. Stern Architects (RAMSA) is behind the 40-foot-wide mansion’s deft combination and opulent design. When asked about the inspiration behind its construction, RoundSquare Development founder Robert Kaliner told Robb Report that “we wanted to create a unicorn, a Picasso.” And indeed, one of its most unique elements is a cast-iron spiral staircase that once led from Lennon and Ono’s apartment to a roof terrace but now, fully restored, connects the the parlor-floor living room to the rear garden.

In the foyer, a skylight caps an epic elliptical staircase, featuring Venetian plaster walls, bronze spindles, and a lacquered wood banister that complements the patterned white oak flooring at each landing. In the capacious nearby living and dining room, which spans the full width of the house, you get the first glimpse of the tall and oversized windows that flood the home with natural light.

Accessible by stairs or elevator, the expansive kitchen on the garden level is decked out with double islands featuring White Danby marble counters. A den warmed by a fireplace and a window-lined breakfast area sit opposite, spilling out to the 40-foot sunlit garden with a marble fireplace of its own.

There are five bedrooms in all, one on the garden level that is well-suited to guests or staff, while the primary suite sprawls over an entire floor with a sitting room, two dressing rooms, and a private terrace. Three additional terraces are dotted with mature plantings. Other highlights include a navy-painted study, a top-floor office that could be made into another bedroom, as well as a plush screening room, a fitness space with a sauna, and a 1,600-bottle wine cellar.

The ultra-posh Frankenmansion—the result of two or more neighboring homes being combined into one—made headlines when it was first listed last fall, and the New York Post reported it would set a new downtown record if sold for its asking price. The $75 million listing is held by Leslie Garfield.

Combining side-by-side townhouses has been a trend in New York and other high-density urban communities for at least a decade. Just ask Sarah Jessica Parker, Madonna, or tech titan Sean Parker, who all own a so-called Frankenmansion in the Big Apple.

Click here for more photos of the West Village mansion.