Although anyone who visits Karen Valentine and Bob Coscarelli at their impeccably preserved 1958 prefab in Michigan City, Indiana, would call them lucky to be stewards of such a rare gem, they didn’t always feel that way during the quest for new housing.

Having sold their home in Chicago and ready for a lifestyle change, Valentine, a technology and service development director, and Coscarelli, a commercial photographer, first hired an architect to build on a countryside lot. When that project crumbled, they enlisted another architect, but this time a lack of skilled craftspeople and a ballooning budget forced them to scrap the new design and sell the property. “It was a hugely time-consuming nightmare,” remembers Valentine.

Switching tactics, the couple began to search for a modest midcentury dwelling. This wasn’t proving fruitful, either—until their realtor sent them a listing for a three-bedroom, two-bath prefabricated home about three miles from Lake Michigan, boasting interiors by master furniture designer Paul McCobb. The Frost House, named after forensic pathologist Dr. Robert Frost and Amelia Frost, who had lived there for over 50 years, would also carry the first-edition Knoll furniture that had originally come with the property. “It was essentially the house that we were trying to build,” says Valentine. “We put an offer in without even seeing it.” So anxious was she to own the residence, in fact, that she outbid herself three times.

Shortly after Valentine and Coscarelli purchased the home in 2016, they began to unearth nuggets of information about its pedigree. Their realtor had provided a brochure that identified the prefab as designed by architect Emil Tessin for the now-defunct Alside Homes Corporation based out of Akron, Ohio, which had held a patent for the structure’s aluminum paneling. Their new neighbors provided a stack of Alside Homes sales materials, floor plans of various models, and even a script that had been written for salespeople during home tours. They determined that the Frost House had been a sales model for the company, and that Tessin had been the son of Emil Albert Tessin, the legal guardian of Florence Knoll.

The first time that Coscarelli visited the home, he was on a photography assignment in the area. “Before I was looking in rooms, I was turning furniture upside down and looking at the Knoll stickers,” he recalls. “It was a profound discovery to find a unique house with a stunning, [Piet] Mondrian look with all this furniture that had literally never moved. It had been staged there by Knoll. It was like walking into a museum or time capsule.”

To document their research into the history of the Frost House, Valentine and Coscarelli launched a website and Instagram profile, both of which have prompted people the world over to share their stories and knowledge. “The online community has been amazing in helping us piece [information] together,” says Valentine. An Instagram commenter identified the glass partitions in the residence as Paul McCobb-designed, and sent magazine advertisements from the 1950s. Another visitor told them that his father, Philip Harrington, had photographed the modular home for a 1962 issue of Look Magazine. The article names the Alside construction as a house of the future and reveals that at the time, the company aimed to build 200 homes a day by the end of the year.

To find more Alside homes, Valentine scours old newspapers for advertisements run by authorized builders, and uses Google Maps to locate models in the area. “You can fairly quickly identify the roofline from the satellite view,” she shares. Out of the 12 Alside prefabs still remaining, most have pitched roofs, and none are as perfectly preserved as the Frost House, making it a rare treasure. The original kitchen appliances and bathroom fittings and fixtures are all intact, and aside from some necessary repairs, Valentine and Coscarelli have left everything as it was in 1958.

Stewards of the past, the couple also look to the home’s future: they are currently adding a pool to the 0.75-acre lot, have plans to convert the basement into a rumpus room, and are working to earn a designation as a National Historic Landmark.

To learn more about the Frost House and keep up with the continuing life of the property, visit the website.