The historic Yellow House in downtown Edgartown is set to have a dash of red on its awning this summer, with the athleisure company Lululemon signing a multi-year rental deal to move from its former location across the street and become the restored building’s first retail tenant in two decades.

It’s a rapid transformation for the 18th century building that only six months ago was barely even yellow, its smashed windows, stripped shingles, decaying roof and gray siding all daily reminders of nearly 20 years of neglect in the heart of Edgartown’s main street.

Over the winter the once-dilapidated building, now owned by the town and leased to businessman Christopher Celeste, has been the subject of a $2.5 million makeover by Conover Restoration. The smash of sledgehammers and grind of heavy machinery have been daily indicators of the expansive public-private project. During a walk-through this week, project manager and contractor Gery Conover said the work is on schedule and set to be finished by May, with Lululemon planning to open around Memorial Day.

And the Yellow House is now officially yellow again, thanks to a recent paint job.

“Our feeling all along was how do you activate the corner of Summer and Main,” said Mr. Celeste. “This is the top of Main street — one of the best locations in Edgartown — and it has lain fallow for 18 years. We hope this will bring it back to life.”

The story of the Yellow House is part history, part saga. Dating to 1750, the colonial Georgian structure once belonged to Capt. Charles Pease and is one of the oldest buildings on Main street. Owned for decades by the Hall family and formerly home to a bookstore, the building was left unoccupied for decades and fell into disrepair in the 21st century.

Three years ago, the town decided to take the property by eminent domain, paying the Halls $3 million for the building and surrounding land. After a series of starts and stops and some legal wrangling over a public bid process, Mr. Celeste and his daughter Julia Tarka signed a 30-year lease to take over the property and rehab it. The lease provisions include $100,000 in payments to the town and a commitment to complete a full renovation of the property to make it suitable as a commercial retail space.

The Celestes already own and operate Rosewater Market & Takeaway, one door down from the Yellow House on South Summer street, Rosewater Wine & Spirits on Main street, and the Dairy Queen franchise on Upper Main street. The family has also torn down a small retail building on Summer street that is now a two-story building housing the children’s clothing store, Rosebud.

Work began on the Yellow House portion of the project this winter by Conover Restorations. Although a tear-down would have made financial sense, Mr. Celeste and Mr. Conover said this week, the town and historic district required the developers to renovate the building. The building has been extended approximately 15 feet on its western side, and a far wing was taken out because it was not salvageable. Other than that, it looks like a newer version of the Yellow House of old.

“It’s not a restoration, but it is a rehabilitation, if you will,” Mr. Celeste said. “Where we could, we’ve kept as many materials as possible. The goal was, if you looked at it from the outside, it would look like a spiffed up version of the old building. And from the inside, it was built to last . . . There’s some funky aspects of how the house was originally built.”

Walking through the building this week, those funky aspects were readily apparent, history literally seeping out of the old floorboards and walls. The original building had a dirt floor cellar, so the first step in the restoration involved jacking up the 30-ton building six feet and replacing its foundation. That process unearthed ancient glass bottles and a 1903 theatre ticket to a Shakespeare festival in Oregon.

The building also had numerous twisted tree logs that were used as supports in the walls. Mr. Conover intends to save as many of them as possible. He has also preserved nearly all the 200-year-old timbers in the second-floor apartments, and plans to leave them exposed when the building is completed.

“It’s some thrift-Yankee type thing,” he said. “That’s just the way they used to do it in the old days. You take a tree, and you flatten it off and put in the stud. One hundred per cent original and in its original location.”

The early plan for the restored building was to house two businesses on the first floor and have three apartments on the two floors above. But that changed when Lululemon said it wanted the entire first floor retail space and could commit to at least a five-year lease, with opportunities to extend it for multiple years further, Mr. Celeste said. He said he received a handful of interested applicants over the winter, but that Lululemon was a trusted renter who he believed would benefit the financial interests of the town, which owns the building.

“I’m really happy about it,” Mr. Celeste said. ‘They’ve been in Edgartown for six years, contributed to the community, invested in programming, and even though they’re a national business, they’ve shown that they can provide a lot to downtown Edgartown as well.”

The retail space is about 1,500 square feet, and will have a storefront and entrance on Main street. Lululemon is working with the builders to design the space to their specifications — although the space will still have the ability to be sectioned into two retail spaces. Mr. Celeste said he intends to rent one of the apartments to Lululemon’s manager, and hopes the other two apartments will go to workers in Edgartown. He said Lululemon plans to be open 10 months of the year.

“Their intention is to not just be a seasonal location,” Mr. Celeste said. “Edgartown is a charming, walkable business district, and for those of us trying to operate year round business — we understand you are trying to make friends in the winter and money in the summer. Those businesses open in the winter do it because they understand part of what makes the Island feel alive. This will help that.”

Rosewater Market is also open year round, save for a brief closure after Christmas.

Mr. Celeste said the $3 million investment was not without risk. The building’s former owner, attorney Benjamin Hall, has brought a number of legal challenges, including to the eminent domain taking by the town and subsequent permitting decisions by the Edgartown zoning board of appeals and historic district commission. Although some complaints have since been dismissed, others remain pending in superior court. The town cannot indemnify the family against any rulings made by a judge.

Mr. Celeste said the legal disputes pose no threat to the project’s May completion date.

“We’re not stopping until someone tells us to,” he said. “My hope is that we have not done this all in vain and that we are not at the receiving end of a negative legal outcome.”

Meanwhile, Mr. Conover and his team are working on the building’s final touches, finishing walls, staircases and adding the Yellow House’s characteristic green shutters. For the town, the project represents a major commercial redevelopment — on full display in the heart of the historic village, with its distinct New England architecture.

“That entire part of the block has been a walk-by zone,” Mr. Celeste said. “I think it is going to be transformative,”