It is an out-of-the-way house on Staten Island, the windows boarded up, the basement sloshing in an inch or two of water. It has been a New York City landmark longer than tall ones like the Empire State Building and the Chrysler Building, busy ones like Grand Central Terminal or cultural ones like Carnegie Hall and the Metropolitan Museum of Art.

Its significance is that it was where important ideas hatched in one important owner’s mind in the mid-19th century. The yard, bigger in those days, was where he taught himself about trees and soil — and, some of his fans say, about a newfangled concept, public parks.

The parks part matters because the owner was Frederick Law Olmsted, before he and Calvert Vaux designed Central Park in Manhattan and Prospect Park in Brooklyn and they became America’s first famous landscape architects.

The city bought the house 12 years ago. It appears no closer to becoming a museum or a visitors’ center than it did then. Signs in front are deliberately unwelcoming — “Historical site — no trespassing” — as if signs would deter vandals.