NEW YORK, NY.- The James A. Bailey residence at St. Nicholas Place and 150th Street in Harlem, built in 1888 for the less flamboyant partner of the Barnum & Bailey team, is a three-ring circus of architectural elements: a Romanesque Revival tower, curvilinear Flemish gables, a high chimney adorned with Tudor roses, even a heraldic carving of a medieval knight’s helmet over the front door.

A show house for a showman, the limestone mansion is an unlikely survivor of the apartment house construction that swept away other Gilded Age residences on St. Nicholas Place, a spur of St. Nicholas Avenue that stretches north from 148th Street like a railroad siding. By the early 2000s, however, the mansion was in dire distress, its elegant interior ravaged by a pack of inbred dogs and one of its four chimneys tilting perilously.

Though the building was designated a city landmark in 1974, preservationists worried that an unscrupulous investor would buy it and hire lawyers and engineers to persuade the city it needed to be demolished. Instead, the leak-plagued structure was saved by an enterprising couple who scraped together $1.4 million to buy it in 2009, amid the depressed real estate market caused by the 2008 financial crisis.

Martin Spollen, 63, and Chen Jie, 59, natives of New Jersey and Shanghai, respectively, have been restoring it ever since, often with their own hands. It has been a monumental effort driven by love and obsession.

“Our main talent is we’re not in a hurry,” Spollen, a physical therapist, said of the restoration. “So that goes along with not being really rich.” Even with the cash raised from renting out the mansion as a location for television shows like “Law & Order” and “Boardwalk Empire,” the couple expects the project to take another five to 10 years to complete.

James A. Bailey was born James McGinnis in Detroit in 1847. After being orphaned as a child, he landed a job with a traveling circus managed by Frederick Bailey, whose last name he adopted. By the 1870s he co-owned a circus, which he boldly took on a pioneering tour of Australia before combining it with a London circus. His dash and ambition frequently brought him into bitter competition with P.T. Barnum, until the two rivals joined forces in the early 1880s as “the Greatest Show on Earth.”

But Bailey’s health failed, and he made plans to retire in the St. Nicholas Place mansion, filling its 25 rooms with curios from his world travels. In 1886, ground was broken. An avid horseman, Bailey also commissioned a terra-cotta-ornamented stable down 150th Street near Convent Avenue.

Bailey’s residence, the vision of architect Samuel B. Reed, who later designed a mirror-image sister house in Cortland, New York, was featured on the cover of Scientific American in 1890. The magazine extolled the house’s “harmony of design” and its wealth of mosaic-like stained-glass windows, created through an innovative process patented by Henry F. Belcher.

Alice Cooney Frelinghuysen, a curator of American decorative arts at the Metropolitan Museum of Art, said she was “flabbergasted and overwhelmed by seeing so many Belcher windows in one site and in their original setting” when she visited the Bailey house around 2009.

Of the home’s 100 windows, some 70 include vivid stained glass.

“It’s completely special,” Frelinghuysen said. She surmised that the Baileys, “like many people who could afford a proper decorative interior, were trying to work toward a ‘gesamtkunstwerk’” — a total artwork, in which all the decorative elements worked together toward “making the whole house a work of art.”

But no house could contain the indefatigable Bailey for long. He rejected retirement and rejoined Barnum under the big top by 1888, “trotting around,” The New York Times reported, “giving directions in a calm voice that permits no dispute.”

As apartment house development encroached upon the neighborhood, Bailey and his wife, Ruth, decamped to Mount Vernon, New York. The Harlem house was sold in 1904, and Bailey died two years later, at 58.

In 1951, Marguerite Blake, who grew up in the neighborhood, realized her childhood dream by buying the Bailey mansion with her husband, Warren. The couple lived upstairs, while Marguerite Blake used the parlor level, including Bailey’s old reception room, as the M. Marshall Blake Funeral Home.

The Blakes were such conscientious stewards of the house that in 1981 they were honored for its restoration at a ceremony at the Urban Center on Madison Avenue.

But things took a dark turn. Marguerite Blake was robbed at gunpoint in the mansion, the thieves making off with the myriad gold bangles she wore from wrist to elbow. For security, the Blakes adopted German shepherds, which the childless couple loved like family.

In time, “the Blakes got older and the dogs got more inbred and uncontrollable,” chewing through balusters, clawing at the inside of the front door and relieving themselves in the home, said Michael Henry Adams, a Harlem preservationist and longtime friend of the couple. “It was very disturbing.”

In 2000, a fire ignited on an upper floor. The damage was limited, but windows were knocked out by firefighters, and the house deteriorated further.

In 2008, at age 87, Blake put the mansion up for sale for $10 million. But no one would touch it at that price, as the house had more than 30 active leaks and reeked horribly from years of dog waste.

Spollen and Chen, who goes by Jenny, were undeterred. Though the basement floor was riddled with holes large enough to fall through, they observed that the house’s bones — including 21-inch-thick internal supporting masonry walls — were remarkably solid.

The mansion’s lack of a certificate of occupancy meant that no bank would lend them a nickel, so the couple assembled a patchwork of loans from friends and family to help buy the place.

But the pre-closing walk-through turned into something out of a horror film.

As the real estate agent led the couple through the basement with a flashlight, they heard the meowing of feral cats who had crawled through a broken window. Then Chen felt a creepy swarming sensation on her legs.

“I turned the light on my leg, and believe me, in my whole lifetime I’d never seen so many fleas,” she recalled. “My leg was covered. I was screaming.”

Instead of bringing Champagne for the housewarming, friends brought insecticide. A sustained bombing campaign was necessary to eradicate the pests.

The mansion “was a wreck, and I thought, These people are absolutely insane,” said Frelinghuysen, the Met curator, recalling her visit soon after the couple purchased the house. But she was touched, she said, by Chen’s and Spollen’s “spirit of confidence that they were going to make this work.”

To remove the stench of dog urine from the oak herringbone floors, the couple donned rain boots and applied baking soda — more than a ton of it in total — hundreds of times over three years. To shore up the subbasement ceiling, they cannibalized scores of joists they salvaged from dumpsters around town.

Short on funds, they have often been compelled to learn specialized skills on the fly. They have built their own scaffolds, from which they have installed and finished historically appropriate windows.

When their veteran stonemason returned to England before completing restoration of the troubled perimeter wall, Chen and a cousin, Xu Haihua, known as Jim, took up the cause.

On the first day, despite working for hours, they managed to install just one stone.

“On the second day, three stones,” Chen said. “On the third day, I got seven stones, and then we got going.”

For the first couple of years, she watched and learned as their carpenter repaired window sashes and other details. When he left their employ, they replaced him with Xu, who had recently immigrated from China, where he assembled televisions in a factory.

“Jim had no background in carpentry ever,” Spollen recalled. “We said, ‘We expect greatness.’”

Xu has indeed become skilled, working in the home’s basement wood shop to replicate the intricate profiles and mortise-and-tenon joinery of the mansion’s original windows, many dozens of which had been replaced with aluminum eyesores.

“I’m shocked at how beautiful this house is,” said Xu, who shared a two-bedroom apartment with three generations in China and now sleeps in the grand bedroom once occupied by Ruth Bailey. “It feels so good, and gives me a lot of challenge and inspiration to do good woodwork.”

Adams, who featured the Bailey house on the cover of his 2002 architectural history, “Harlem, Lost and Found,” said that the dereliction of the Bailey house during the Blakes’ latter years scared away developers who might have sought to tear it down or build a sliver tower in the backyard.

“The fact that Martin was able to get it at an extraordinary price,” Adams said, “and the fact that he has this extraordinary ethos to do this long, drawn-out restoration process without being a very wealthy person, is a miracle.”

This article originally appeared in The New York Times.