The New Canaan Preservation Alliance announced Thursday it's petitioning a Stamford Superior Court judge to block the town's approval of a plan to replace the library.

At issue is the original 1913 building, which preservationists want to keep as part of the new facility.

The library released a statement, calling the lawsuit "an unfortunate step."

It goes on to say, "Nevertheless, the library will move forward as planned and will start construction imminently. At the same time, we will continue to work with the town to develop a plan to meaningfully preserve portions of the original structure in accordance with the planning approvals."