Call it a tragedy of errors: Brookhaven’s historic Mott House collapsing, undermined by town contractors hired to clean it up. Brookhaven Supervisor Mark Lesko vowed to rebuild, using salvaged material. “Out of these remnants of the Mott House we intend to build something special,” he said.

Lesko also pledged an investigation, and a review of the town’s 147 historic structures, all good steps. Brookhaven’s hard lesson should apply to all endangered Long Island landmarks: Re-use them, or lose them. And protect them.

Suffolk County legislators have taken steps to save Nicola Tesla’s fabled Wardenclyffe laboratory in Rocky Point–designed by famed architect Stanford White–and the 13 acres surrounding it.

And East Hampton town leaders recently celebrated the restored exterior of the Montauk Playhouse; but Supervisor-Elect Bill Wilkinson raised doubts about using a new town hall complex that links eight relocated historic structures.

Nassau County recently announced plans to restore Roslyn’s ancient Grist Mill, and William Cullen Bryant’s Cedarmere, splitting the $4.3 million cost with the Roslyn Landmarks Society.

Also credit Tom Suozzi and county legislators for restoring the long-neglected county court house. But, sadly, a nearby Garden City landmark languishes.

St. Paul’s School is, unbelievably, on the road to demolition. Village hearings will soon weigh the environmental effects of a $6 million demolition plan. Preservationist groups are rallying in opposition. More power to them.

Can you imagine a day when debris from St. Paul’s could be found in a dump?