A historic decades-old mural was painted over at a New York high school during a repair project

(CNN)For nearly 80 years, a well-worn but well-loved work of art adorned the third-floor ceiling of a New York City high school.

The mural -- a shimmering night sky with golden-yellow stars -- is a piece of history from the New Deal era when the country commissioned hundreds of artists to brighten up buildings and public spaces during the dark days of the Great Depression.
But now, the beautiful mural "Constellations" is slathered with bright blue paint -- painted over during a repair project at DeWitt Clinton High School in the Bronx,
    "It was probably a pretty thoughtless and negligent act that this happened and it never should have happened," said Harvey Smith, the president of the National New Deal Era Preservation Association.
      A constellation painted on the ceiling in "Constellations" before it was covered last November
      He finds the event troubling because many New Deal murals are priceless pieces of art that carry historical significance.
      "What the New Deal did was bring art to the general population," he told CNN. " And that art often carried messages of everyday life that recorded local history."

      Painting over history

        "Constellations," was the work of German-born artist Alfred Floegel as part of the nation's Federal Art Project of the 1930s. A second Floegel work covers the walls on either side of the mural. Together, the murals took six years to complete.
        The ceiling of a hallway at Dewitt Clinton High School before "Constellations" was painted over
        In November, crews painted over "Constellations" as the school repaired damage to its roof, said Doug Cohen, a spokesman for the city's education department.
        Frank da Cruz is a national associate at the Living New Deal project at the University of California, Berkeley, which captures the impact of the New Deal on Americans. He said the mural was in pretty bad shape.
        "I hope they will restore it and I hope they learn something from having to restore it," da Cruz told CNN

        Restoring what was lost

        Dewitt Clinton High School, where a historic New Deal-era mural was covered last fall.