PORTLAND — In 2011, Freeport developer Kenn Guimond, who runs The Guimond Group, took on the renovation of a building of historical significance but in derelict condition.

Located in the Congress Street Historical District, which is also part of Portland's Arts District, the renovation of 660-662 Congress St. turned out to be much longer and more complicated than he anticipated.

"I was contacted by a local broker who thought it would be an interesting project for me — and believe me, it was interesting," he said. This was Guimond's first historical preservation project in a portfolio, spanning about 40 years, that includes mainly residential and commercial development in the Portland-to-Freeport region. "It's hard to make the dollars work, but the satisfaction is off the charts."

The building, finished in 1886, is known as the George S. Hunt block, named after a Portland businessman who owned the Forest City Sugar Refining Co. on Commercial Street in Portland, according to the Maine Historical Society. In the 1870s or so, according to Guimond, Hunt bought a derelict tenement building at the current site, had it razed, and hired Francis Fassett, a preeminent Portland architect of the time who worked in the Victorian High Gothic and Queen Anne styles. Fassett designed the current Queen Anne building, with features typical of the style that include brick-relief columns and pediments, a slate roof and bay windows. Hunt lived next-door to the building. Storefronts were added in 1912 and 1950. The building is also distinguished by its triangular shape.

The building was subsequently owned by a number of people, said Guimond. Its last commercial tenant, on the ground floor, was an antique store. Previously, Kenneth Aherne's Tailor Shop occupied the space. The upper two stories were always residences. Originally designed as one unit per floor, the residential space was divided several times into smaller spaces over a 30-to-40-year period.

After several years of vacancy, Roxanne Quimby, the philanthropist and Burt's Bees founder, bought the building in 2009. She planned an artist studio and gallery space, according to a 2011 Portland Press Herald story, but in 2010 the interior was severely damaged by fire. Quimby eventually put the building up for sale.

"So by the time it got to my sphere, it was damaged both by disrepair and by the fire," Guimond said.

Guimond hired Present Architecture of New York City to design and oversee the restoration. His son, Andre Guimond, is a principal in the firm, which got its start around the same time Kenn Guimond bought the building, making this one of the firm's first projects.

Due to unexpected structural problems, the expected 18-month project took four years.

"It wasn't until we got our engineer in the building that we found it in much greater disrepair than we thought, and it would take pretty much a complete restructuring of the interior," Kenn Guimond said.

Interior structural components failed to meet modern engineering codes, yet couldn't be stripped out wholesale or the building's brick shell could have been compromised. Instead, supporting structures such as beams and joists were replaced and surfaces releveled in a section-by-section surgical approach.

Since there are no images of the original interior, Present Architecture designed a contemporary look, with open spaces, white walls and ceilings and little trim. Removal of a roof-to-foundation chimney provided flexibility for the floor plan. Innovative lighting includes custom-designed skylights and LED fixtures tucked into ceiling coffers for a wash of soft illumination into living spaces. A shared stairwell features custom metal balusters and white oak treads. All systems were replaced.

The exterior was sound but needed work, including a new slate roof, new copper gutters, mortar replacement and new windows that honored the original design.

Renovation to the historic building had its challenge, said Andre Guimond. Non-historic downspouts had to be replaced. The team discovered roof-to-ground pockets, to accommodate historic downspouts, hidden inside the brick walls.

"It's not easy to do, because you're sluicing cold rain water through the inside of your walls," said Andre. "But we thought it would be great way to restore the building to its original look and clean up the façade, so we incorporated that."

They ran into other surprises. For example, a new water line for sprinkler systems had to cross Congress Street, which meant closing the street. The closure took longer than anticipated when street crews found, first, cobblestone paving down one layer, which had to be dug up. Then they found old trolley lines down a further layer, which had to be cut.

All together, 7,600 square feet now comprise one high-end apartment on each of the two upper floors, commercial space on the ground floor and a brick-and-stone space below the sidewalk level that could be useful for the commercial tenant.

The purchase price was in the mid-$200,000s, and renovation cost over $2 million. Guimond supplied 60% of the financing and received bank financing for the rest, with federal and state tax credits available for designated historic structures offsetting costs.

Guimond recently began marketing the spaces; the first residential tenant was slated to move in late April. Like the majority of other Guimond Group design and build projects, this will be kept in the portfolio.

"To us, it's a piece of history, not just another commercial project," said Kenn Guimond. "It means a lot to me. I've been in the business 40 years, and done all sorts of custom homes and office buildings. But this has been the hardest project I've ever done, because it was such a delicate process and we wanted to respect the integrity of the original design. We want to preserve this building in such a way that it should be here for another 140 years."