New York City’s Landmarks Preservation Commission would do well to turn down the Frick Collection’s proposed expansion, which imagines replacing a prized garden on East 70th Street in Manhattan with a clumsy addition. The city should avoid another self-inflicted wound, and there are other options.

The plan, announced last month, ran into early headwinds. New Yorkers have seen the consequences of trustee restlessness and real estate magical thinking, which destroy or threaten to undo favorite buildings. Not so long ago, the Morgan Library & Museum, another Gilded Age landmark, built an addition that flopped. The New York Public Library wanted to disembowel its historic building at 42nd Street before thinking better of it.