A string of rustic shacks in the outermost dunes of Cape Cod, which served as inspirational getaways for Eugene O'Neill, Jack Kerouac and other solitude-seeking writers and artists, on Friday won national historic designation.

But preservationists warn that the National Park Service designation may not be enough to save the 17 primitive huts from eventual demolition.Park Service officials at the Cape Cod National Seashore fought placing the dune shacks on the National Register of Historic Places. But the Massachusetts Historical Commission recommended in September that the huts be placed on the register, and late Friday officials at the National Park Service in Washington approved the designation.