Q. The lobby of the Arsenal, the former weapons storehouse in Central Park, which is now the headquarters of New York City’s Department of Parks and Recreation, has an odd feature for such a utilitarian building: a huge crystal chandelier that would be at home in an opera house. How did it get there?

A. The origin of the chandelier is one of the great mysteries of the parks department, which keeps extensive historical records about virtually all its facilities and statuary. “All we know for sure,” the agency said in a 2005 newsletter, “is that the chandelier was crafted out of high-quality crystal in the 1920s or 1930s. From historical photographs, we know the chandelier was in place by 1936. Countless investigations have subsequently led to dead ends.”

Not that the department hasn’t tried to find out. Researchers, it said, have gone to curators from the Metropolitan Museum of Art; the Historic House Trust; proceedings of the Board of Aldermen, which would have had to approve its purchase; Christie’s auction house, whose experts have cleaned it several times and said it is crystal, but without a maker’s mark; and even Robert A. Caro, the biographer of Robert Moses, who became parks commissioner in 1934.

The chandelier seems just the kind of thing the imperious Moses would have ordered, but Mr. Caro, in “The Power Broker: Robert Moses and the Fall of New York,” wrote: “Moses was never to have an office at the Arsenal and was to visit the building infrequently during his 26 years as park commissioner because he didn’t want to be accessible to departmental employees.”