Jim Steinman, who died last year at 73, left behind one of the most distinctive catalogs of music in history, filled with chart-topping hits written for the likes of Meat Loaf, Bonnie Tyler and Celine Dion. With songs ranging from the restless (“All Revved Up With No Place To Go”) to the wrenching (“For Crying Out Loud”), Mr. Steinman spent decades establishing himself as a sophisticated songwriter with the spirit of a teenager.

“As far as Jim was concerned, life was about being forever young, and lusting after this and yearning after that,” said David Sonenberg, Mr. Steinman’s longtime friend, manager and now the executor of his estate. “He was going to be 17 forever, and in some ways he was.”

But perhaps nothing evokes Mr. Steinman’s legacy like the Connecticut house where he lived alone for some 20 years — a majestic museum of the self, attached to a quaint cottage in the woods of Ridgefield. He spent years expanding and reimagining the house, transforming it into an embodiment of his own eccentric, complicated personality.

“The house — it’s a trip, it’s extraordinary, it’s one of a kind,” Mr. Sonenberg said. “People would walk in and their heads would spin.”

Mr. Steinman, a lifelong bachelor who had been in declining health for years, left no instructions about what he wanted done with the house after his death. Now his longtime friends are putting the property up for sale — with a provision: It is being sold “as-is,” which in real estate lingo normally means “in terrible condition.” In this case, it means that the sale includes nearly all of Mr. Steinman’s personal belongings, which remain in the house: the gothic furniture, spooky artwork, wall-mounted records, grand piano, even closets full of clothing.

“We are going to try to keep Jim’s vision and legacy intact,” said Jacqueline Dillon, Mr. Steinman’s longtime creative assistant and close friend. “Jim has been a pop-culture fixture for 50 years.”

Their hope is to sell the house — which, despite its 6,000-odd square feet, has just two bedrooms — to a musician, artist or writer, or someone seeking a creative retreat or performance space. The asking price is $5,555,569 — the $69 is a tribute to Mr. Steinman’s beloved Amherst College, where he graduated with the class of 1969 — and the annual property taxes are around $32,000.

Ms. Dillon described Mr. Steinman — by all accounts a reclusive, nocturnal introvert — as “super-shy, but always so kind, and with a lightning-quick wit.” She met him three decades ago at a concert, she said, and was soon recruited to launch his website, jimsteinman.com, to connect with fans and to monitor press mentions.

She is now helping to oversee the house sale. “This is not a sale where there is a comparable,” she said.

As with many of Mr. Steinman’s grandest achievements, the house almost never happened. It was Mr. Sonenberg who found it nearly 30 years ago. Driving through Ridgefield, he spotted the home on a secluded lot of about 1.5 acres and thought it would be perfect for his friend.

“The house was so charming,” said Mr. Sonenberg, whose own artistic dreams were dashed after he met Mr. Steinman in the 1970s. “I wrote a song called ‘Pear Tree in the Shade,’” he said. “Jim wrote a song called ‘Total Eclipse of the Heart.’”

Mr. Steinman, who started writing musicals for Joseph Papp at the Public Theater before conquering the pop charts with songs for Meat Loaf’s 1977 smash album “Bat Out of Hell,” was seeking a place to hide away and work. After years of delays, he and Meat Loaf (born Marvin Lee Aday) were completing production on “Bat Out of Hell II: Back Into Hell,” which (to no one’s expectation but their own) would become one of the best-selling albums of the 1990s.

Mr. Sonenberg suggested that Mr. Steinman buy the Ridgefield house: “I said, ‘It’s perfect — you’re by yourself, you never have any guests.’ And he said no, it was too small.”

Around that time, while Mr. Steinman was working with Andrew Lloyd Webber on the musical “Whistle Down the Wind,” he visited Lloyd Webber’s manor house, Sydmonton Court, in Hampshire, England, and “was just blown away,” Mr. Sonenberg said.

So Mr. Steinman decided to buy the Ridgefield cottage, paying about $425,000, and convert it into a soaring sanctuary, a creation as epic as his music.

“It is really special, almost otherworldly,” said Laura Freed Ancona, the listing agent, of William Pitt Sotheby’s International Realty. “Yes, it was a roof over Jim’s head. But it was also a creative space for him.”

Ms. Ancona said the plan now is to start with private and group showings, and to reach out to various arts and cultural organizations, looking for a potential buyer. “We want to cast as wide a net as possible,” she said.

The house, Mr. Sonenberg said, could be sold to a school or institution and used for a combination of living, office and performance space.

Mr. Steinman, who grew up primarily in Hewlett Harbor, on Long Island, moved to Manhattan after graduating from Amherst and was hired by Mr. Papp, who was captivated by songs Mr. Steinman had written for his senior project, a rock musical called “The Dream Engine.” It later morphed into “Neverland,” inspired by Peter Pan, the boy who never grew up. (A few years after getting the Public Theater gig, Mr. Steinman, always pitching, wrote a letter to Mr. Papp asserting that “writing and conceiving serious strong musical dramatic works” was something “I really think I can do better than anyone I’ve ever come across or heard about.”)

Back then, “his taste in décor was zero,” said Frederick Baron, a college friend, who remembered visiting Mr. Steinman in a spartan apartment with bare walls and a refrigerator holding only leftover pizza and spaghetti.

“He lived the life of the mind,” Mr. Baron said. “He had this extraordinary level of creativity. He was truly brilliant. All of his life energy was in that keyboard.”

After Mr. Steinman started making serious money, he bought a two-bedroom apartment in a postwar co-op overlooking Central Park. That’s where he met Bonnie Tyler, who would top the charts in 1983 with the Steinman-penned “Total Eclipse of the Heart.” She and her manager were welcomed with a trail of M&Ms leading to his door.

Mr. Steinman later used that home mostly as an office and for wine storage, and moved into a rented house in the woods of Putnam County, N.Y., with a bunch of cats.

“Jim was a homebody, and being in the city was quite busy for him,” Ms. Dillon said. “He was always being asked to go to people’s shows. Leaving the city removed him from having to do a lot of things. He didn’t go to big events. He let his art do the talking.”

He called the Ridgefield cottage “the house that ‘Bat II’ built,” Ms. Dillon said. “Jim used the expression ‘cottage to compound.’” The album opened with the hit “I’d Do Anything for Love (But I Won’t Do That),” with an accompanying video depicting Meat Loaf as a “Beauty and the Beast”-like recluse living alone in a gothic mansion.

To expand the house, Mr. Steinman hired Rob Bramhall, a Boston-based architect, eventually spending about $6 million. Mr. Bramhall worked on the project for the better part of a decade, more than doubling the house’s size. After their initial meeting, Mr. Bramhall sent Mr. Steinman a book by the influential California architect Bernard Maybeck, he said, and “Jim knew I got his sensibility.”

The style was English Cotswolds. “Jim wanted the gables, from left to right, to become slightly larger,” he said. “I remember doing skull-and-crossbones for the faucets in the powder room off the great room. Some of the wall light fixtures were made from aircraft parts.”

Although Mr. Bramhall met with Mr. Steinman in Manhattan and helped him select and place the artwork, “Jim never saw the house until it was done,” he said. “It was a fun and interesting project. I haven’t done anything like it since.”

The original part of the house — bright and sunny — includes a large living room with Mr. Steinman’s many gold and platinum albums on the wall, open to an equally large kitchen with a dining nook. There’s a laundry room and a sunroom, although Mr. Steinman preferred the dark.

“That end of the house represented normalcy to him,” Ms. Dillon said.

In the dining room, the table is set with Mr. Steinman’s china, in the Royal Copenhagen Fairy Tale pattern — not that he ever used it. He preferred to eat off disposable tableware, specifically blue Solo cups and Chinet plates.

In the den, or “viewing room,” he enjoyed watching singing competitions like “American Idol,” and critiquing the judges. He also watched cooking shows, Yankees games and “Jeopardy!”

“He could listen to music, watch a TV show and type a letter” all at once, Ms. Dillon said. “His mind never stopped working.”

The “good room” — not to be confused with the great room — holds one of his wheelchairs, which he needed after suffering a series of strokes. Of course, “it was a crazy wheelchair, like a Batmobile,” Mr. Sonenberg said.

Mr. Steinman referred to the unused guest room as the “Wendy Bedroom,” after the heroine of “Peter Pan.” The plush bear on the bed hails from the Great Ormond Street Hospital for Children, in London, which owns the intellectual property rights to “Peter Pan” and denied Mr. Steinman’s request to stage a rock musical based on the story, deeming the script — which opened with killer nuns — unsuitable for children.

The addition, all custom made and filled with elaborate and peculiar art and artifacts, starts with the Ring Room, a small, oval space unfurnished save for sculptures on the walls, which are a color Mr. Steinman called obsidian blue. (Obsidian was the name he gave to Neverland’s city.) The ceiling is dotted with LED stars.

“And that leads you from this sweet cottage into this other universe, which is modeled after Steinman’s vision,” Mr. Sonenberg said. “Jim was the most bizarre guy, but he was the sweetest and funniest and most generous. He was the only genius I ever met.”

The primary suite is at the end of a wardrobe hallway, where the vast closets still hold Mr. Steinman’s many clothes, few of which he wore, although candy wrappers remain in some of the pockets. So many garments are crammed on the racks that “you would think you were in Bonwit Teller,” Mr. Sonenberg said.

Parallel to the wardrobe hallway is a long corridor leading to the great room, lined with patent leather panels and used by visitors — most recently, those working on “Bat Out of Hell: The Musical,” which is touring in Britain and is slated to open in Las Vegas in September.

The enormous bedroom includes a desk, sitting area and aquarium. The art on one wall, “Inferno” by Joseph Grazi, depicts taxidermic bats flying into the maw of an alligator skull. Much of the idiosyncratic art Mr. Steinman collected was by artists from Bayreuth, Germany, the longtime home and final resting place of his idol, the composer Richard Wagner, whose operas enthralled him from childhood. The room is also adorned with items collected from fans and, on the bed, a heart pillow in tribute to the surgeon who extended Mr. Steinman’s life.

Beyond the bedroom is the house’s focal point, the great room, centered around a stainless steel sculpture resembling a cluster of giant quartz crystals — an allusion to Superman’s Fortress of Solitude. Mr. Steinman’s 2013 honorary doctorate from Amherst is on display. A bust of Wagner sits atop a Yamaha piano, although Mr. Steinman composed mostly on keyboards. “He had this uncanny ability to play all the parts on the piano,” Ms. Dillon said. “It almost sounded like a full band.”

Stairs ascend to a gallery overlooking the room. One chair is occupied by a skeleton mid-shriek. Another flight leads to the room at the top, with a skylight and reading chair.

Mr. Steinman often used the tiny kitchenette off the great room, stocked with fresh fruit and cans of Progresso soup. He was a fan of hot sauce, sweet soda and chewy candy. “When I visited him for the first time in his home, he had these containers of gummy bears from the pick-n-mix selection at Dean & DeLuca for $12.99 a pound,” Ms. Dillon said. “Every month, we would get a bill.”

The detached two-story garage has plumbing and electricity, and could possibly be an accessory dwelling unit. Mr. Steinman used it for storage — he didn’t drive or have a license. Despite his love of motorcycles (and songs about them), he likely never rode one. Instead, he filled the garage with copies of his programs and Playbills. “He liked stuff,” Ms. Dillon said.

The question is: Will anyone want Jim Steinman’s stuff? Ms. Ancona is hoping that the property, like Mr. Steinman’s music, will inspire someone looking for something beautiful and a little strange.

“Every house needs its own approach, whether it’s a $500,000 home or a $5 million home,” she said. “You really have to find your audience.”

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