From behind a parapet on the tower of Litchfield Villa, the Italianate mansion that marks the western edge of Brooklyn’s Prospect Park, I was barely able to make out — over treetops and tall buildings — a glint of Gowanus Bay, roughly two miles away. Edwin Litchfield, the railroad and real-estate tycoon who built this house in 1857, would have had no trouble seeing the bay and much of his landholdings out of a second-floor window, from the hilly and largely treeless farmland outside his front door all the way down to the grassy banks of Gowanus Creek, which by the late 1860s had been dredged and straightened, at his behest, into a shipping canal.
Situated at the bottom of a topographic bowl, the Gowanus marshlands were once nourished by more than a dozen sparkling streams. Most of these rills and freshets haven’t been seen for 150 years; following modern convention, engineers either buried them or corralled them into pipes as they extended the city’s streets. But one of these waterways, I learned after climbing down from Litchfield’s roof and placing my ear atop a manhole cover, still seemed to be flowing, right under my feet.