WINTHROP — The mill complex that for more than a century was the heartbeat of the downtown has a whole new avenue to help bring it back to life.

The Winthrop Mills Company Historic District – which includes the former Carleton Woolen Mill – has been entered into the National Register of Historic Places. The designation, which indicates the property has been documented, evaluated and considered worthy of preservation and protection as part of the nation’s cultural heritage, allows the owners to tap into federal and state historic preservation tax credits and seek grants designated for historic properties.

“I wanted to get this on the National Register,” said Lou Carrier, president and chief operating officer of Winthrop Commerce Center LLC, which owns the mill complex. “It’s been such a part of Winthrop’s history from the 18th century on.”

Earle Shettleworth Jr., state historian and director of the Maine Historic Preservation Commission, said in a release that the mill complex reflects nearly 150 years of textile manufacturing in Winthrop. The complex, which contains two separate mills and has eight total contributing historic resources, manufactured wool textiles in the larger complex adjacent to Main Street and manufactured cotton in the smaller complex on Clark Street.

Construction of the existing buildings began in 1882 and continued through the mid-1950s.

“The Winthrop Mills Company was established in 1866, and it was an important local industry employing many residents in town,” Shettleworth said. “At one time it was the largest firm in the country exclusively producing woolen bed blankets and cotton warp.”

Cotton warp is a type of yarn used in weaving.

Carrier and his three partners have owned the complex, also known as the Carleton Woolen Mill, for about 10 years. A description on the Winthrop Lakes Region Chamber of Commerce website says the building is a multiuse facility with 200,000 square feet of leaseable space and is located on 10 1/2 acres. The town has assessed the complex at $4.6 million.

MaineGeneral Medical Center, which leases about 24,000 square feet of space, is the largest tenant, Carrier said. The mill also is home to a cafe, a sexual assault support center and the Winthrop Commerce Center office.

Carrier said the national register designation is an important step in building up the mill’s clientele and versatility. The designation as a historic building makes the mill eligible for state and federal historic preservation tax credits and allows the owners to seek grants for preserving historic places.

“It will make us eligible for some grant money to maintain and further develop it,” Carrier said. He did not know how much money the corporation might receive.

The mill owners still have big hopes for the complex. Carrier said his corporation is talking to people and businesses interested in everything from retail space to elderly housing.

“We have a lot of things on our agenda,” Carrier said.