Signifying another step in the city's gradual shift away from industrial manufacturing, the Hexcel plant on North Mines Road opened its doors Tuesday to local historians as it prepares to demolish the facility to make way for new houses.

Members of the city's Historic Preservation Commission and the Livermore Heritage Guild were taken on a 90-minute tour, which is required for buildings more than 50 years old scheduled for demolition.

"Fifty years is generally considered a period of time in which someone can take in a historical perspective," said Frank Guido, a city associate planner.

The plant currently occupies about 13 acres, though at one point it covered about 40 acres. Steve Darfler, a Hexcel testing manager, said the plant will close for good by mid-2007. The company, which employs about 90 people in Livermore, is consolidating its operations and moving its resources to its base in Salt Lake City.

The site originally was purchased by Coast Manufacturing in 1913, which made slow-burning fuses for dynamite. In 1947, Coast began to focus on fiberglass, and in 1966 merged with the Hexcel Corp. to produce materials for the aerospace industry. At its peak, there were 55 factory buildings at the site, employing 150 people.

When it is all demolished, it may be replaced with about 60 houses in what is termed a "low-density residential" project, though plans are fluid, said Gary Brooks, president of Northbrook Homes, which would build the houses.

Bob Manildi, who worked at the site from 1954 to 1968, was a chemist, a marketing manager and salesman. While the plant is now surrounded by homes, light industry and, not too far away, retail, "Everything from here on out was agriculture" when he worked there, he said.

"I understand the reason for moving the manufacturing facility ... We first moved out here because no one would ever be around," Manildi said. "We weren't going to bother anyone. But now this is all in the middle of the city, in the middle of residential."

Anna Siig of the Heritage Guild said all buildings have a story to tell.

"Everyone should watch a historical building get demolished, because you'll look at it differently after that," she said. "It informs you and educates you."