BANGOR, Maine — The first phase of preparing the future home of the Bangor Museum and History Center is nearing completion.

The work at 25-27 Broad St., known locally as the Circular Block, has involved renovating and restoring the historic former bank building’s exterior and addressing interior structural issues, Russ Harrington, the museum’s board president,said last week.

Left on the to-do list for Phase 1, expected to cost about $2.9 million, are replacing the roof, installing new windows and making the building weather-tight so that it can be closed for the winter.

Harrington said that renovations would be suspended during the winter to avoid the high heating costs the museum would incur if the work were to continue through the winter.

The phasing of future work, however, depends on funding.

“Originally, the plan was to raise $2.9 million. We’ve raised to date $2.6 million and we probably have enough ‘asks’ out there to meet our target by the end of the year,” Harrington said.

That money was raised in the campaign’s “quiet phase,” he said, adding that the fundraising effort has not yet been publicly launched. That, he said, will come later.

“We feel we are very fortunate and very blessed to have the community support that we’ve had so far,” he said.

The next phase, or phases, and cost estimates will be worked out over the winter, with plans to resume construction early next year, Harrington said.

“I think we’d be remiss to even put a figure out there at this point,” he said.

“We have to regroup and make sure we’re on the right path to raise the appropriate amount of money,” he said. “We have to be a sustainable cultural asset for the city and we intend to be. We’re looking very long-term right now.”

As is the case with most old structures, the so-called deconstruction phase turned up some unanticipated issues that needed to be addressed.

When work on a historic structure begins, Harrington said, “it exposes itself to you. The warts really begin to show in the process of taking it apart. You really learn so much more about it, and everything changes” including budget and fundraising targets, he said.

The Circular Block actually consists of three sections, each built at a different time. To that end, he said, the contractor needed to remove floors and strengthen them with structural steel, which Harrington noted has roughly tripled in cost since the renovation project began.

“The other thing that happened is that the economy changed on us,” he said. The nationwide fuel and finance crises could have an adverse effect on museum fundraising efforts.

Once completed, the newly refurbished downtown space will house the museum’s more than 15,000 artifacts, which include an extensive Civil War collection, photographic and fashion collections, as well as a significant archival collection dating to the mid-18th century.

“We really believe that the people of the community see this as a very important project, but it will take time,” he said.

Bill and Sally Arata of Veazie gave the Circular Block, which consists of red- and copper-colored sections, to the museum in November 2005.

Museum officials said at the time that the gift would allow the museum to consolidate its collections to one building and expand its exhibition, education and administrative space.

To that end, plans for the four-story building call for putting the exhibit area, museum store and other public space on the first and second floors, and for placing offices and space for lectures, meetings and other gatherings on the third level.

Archival-quality storage space would be created on the top floor, which will have its own separate air-handling system.

Like other construction companies, Nickerson & O’Day sometimes takes on projects that are more important to the community than the corporate bottom line.

“This is certainly one of them,” Karl Ward, the company’s president, said last week.

“This is more of a socially redeeming project from a philosophical, or core philosophies, point of view. We felt this project was a perfect fit for us,” given the company’s more than 50-year history in downtown Bangor.

In a ceremony held last week, just before the last steel beam being used in the project was hoisted into place up on the roof, Nickerson & O’Day workers paused to remember Adam Lawrence of Corinth, a project supervisor killed in a July motorcycle crash. Lawrence’s widow and family members were on hand for the remembrance.

“Adam loved this project,” Ward said, adding that the young foreman would have been thrilled to have been among those who signed the beam before it was set into place.