Not long ago, I read an article about archaeologists in Greenland who discovered that plants growing above an ancient Norse ruin possessed slightly different chemistry from plants growing nearby. I was taken with the idea that the energy of a forgotten structure, invisible and buried deep underground, may percolate upwards to leave subtle impressions on the surface. It was this that came to mind recently when I discovered Minetta Brook, a hidden stream that flows beneath the streets of Greenwich Village.

I had learned of the stream from an 1865 map of Manhattan, drawn by an engineer named Egbert Ludovicus Viele, which showed marshlands, rivers, and streams crisscrossing the island beneath an overlay of the city’s grid. The map, which is still used today by engineers, showed Minetta Brook beginning as two branches, one originating from a spring at Fifth Avenue and Twentieth Street, the other from a marsh near Sixth Avenue and Seventeenth Street. They met near Twelfth Street, then flowed south down Fifth Avenue, through Washington Square Park, before emptying into the Hudson River at Charlton Street. According to the historian John Fiske, the brook, in the seventeenth century, had been a favorite fishing spot for the Lenape and the Dutch: “a clear swift brook abounding in trout.” By the early nineteenth century, it had disappeared from maps, buried beneath the streets, forgotten. Or perhaps not. There were stories floating around about basements of older buildings in the Village with grates in the floor, through which you could see the stream flowing. I wanted to listen to the stream, smell the water, dip my fingers in, maybe even take a small sip. Wouldn’t that be something. And so I decided to retrace the path of Minetta Brook, going door-to-door, asking everyone I met about the stream that flowed beneath their building.

Iggy, the superintendent at 133 Fifth Avenue, knew all about the stream. “Yeah, yeah.” He was a gnomish man with a mildly harassed air. “It used to flood my elevator pits.” I stopped an elderly couple emerging from their apartment building on Minetta Lane (named for the brook). They’d lived on the street for sixty-eight years. “It’s down there somewhere,” said the woman, with a shrug. In Minetta Tavern, I found a map painted on one wall titled, “Early Dutch Map of the Village shewing the site of Minetta Brook, the Farms and Estates adjoining, & the Properties and Landmarks of our Times.” Outside an antique shop on Downing Street, a man with an aureole of white hair told me, “I’ve lived on top of the stream for seventy years.” I asked him about being able to see the stream in old basements. “People say that,” he said, “but I never saw it.”

Nor had anyone else. I asked a middle-aged man with walrus-like whiskers who lived in a basement apartment on Minetta Street about his relationship to the stream. “It’s only a memory now,” he said.

I spoke to James Mellett, who had searched for the stream twenty years before. He was a geologist. He had used ground-penetrating radar. In Washington Square Park, he set up a fiberglass box containing an antenna, which emitted radar waves down through the concrete, sand, and gravel. But there was too much interference. “I wish I could help you,” he told me, “but I never saw it.”

Walking the stream’s path, I recalled an image I had seen once in a book about the rustic art of dowsing. A man with a steel-colored beard down to his solar plexus held the ends of a wishbone-shaped wooden rod. He walked through an empty field. He waited for the rod to tremble in his hand. An ineffable vibration from below, an invisible waterway.

On West Houston, the stream ran beneath a psychic den called Mystic Visions. In the doorway, I found a sallow woman in a long dress, head wrap, and mascara—a gypsy, or playing the part. A somber-eyed toddler appeared at her side. When I asked her about the stream, she studied me silently. Finally, in an unplaceable accent: “I know nothing about your stream.” The banners in her windows read “Future,” “Present,” “Past.”

On Eighteenth Street, it flowed beneath a Barnes and Noble. I spoke to the property manager on the phone, directed him to an Internet image of Viele’s map. When he saw that the stream flowed under his building, his voice came out breathless, “Oh my god. Oh my god.” He granted me permission to search the basement. I paced up and down, looking for a crack in the concrete where the stream bubbled up from below, listening for an echo of running water. Randy, the store manager who had acted as my escort, watched, perplexed. Perhaps it was only my imagination that the air in the basement felt inordinately damp.

The stream was at its widest on Twelfth Street, where the two tributaries converged. I had read that sinkholes sometimes formed in this street. The stream sidled up alongside a nineteenth-century brick townhouse, which jutted into the sidewalk at an odd angle to accommodate the waterway. No one answered when I rang the bell. The plants growing out of the cracks in the basement stairwell appeared particularly lush. A curtain flickered in the front window; I glimpsed the face of an old woman.

On Downing Street, the stream flowed beneath a nursing home. Through the window, I watched ancient men whispering back and forth across the lobby.

I entered 33 Washington Square Park West, an NYU dorm which had once been an apartment building. On the ground floor, the potbellied security guard escorted me to a small room crowded with rolled-up rugs and black plastic trash bins on wheels. Against the back wall was a bronze sculpture, a cupid with lips pursed. It was a fountain, which had once bubbled with the water of Minetta Brook. According to a 1923 Times article, the fountain’s installation had occasioned a ceremony. “Sharply at 2:30 P.M. , a signal was given, a faucet in the basement was turned and the basin of the fountain began to fill.” A writer called Arthur Guiterman commemorated the brook’s resurfacing with a poem. Via radio, the ceremony was “broadcast throughout the country.” Now the fountain’s basin was bone-dry, and had been for decades, the security guard told me.

I next stepped into 2 Fifth Avenue, an enormous white apartment building. The doorman, an Eastern European man called Peter, showed me a white stone pedestal in the corner of the lobby. On top of the pedestal was a glass tube, four feet tall, that looked like it might have been clear at one point, but was now jaundiced. It was another forgotten fountain, another vestige of the stream. Peter, who had worked in the building for twenty-five years, couldn’t remember the last time he had seen water in it. Next to the entrance was a brass plaque with an engraving.

An erratic brook winds beneath this site. The Indians called it Manette or Devil’s Water. To the Dutch settlers, it was Bestevear’s Killetje or Grandfather’s Little Creek. For the Past Two Centuries familiar to this neighborhood as Minetta Brook.

I couldn’t help but feel that it read like an epitaph. “Visitors come to the fountain,” Peter told me. “On walking tours.” I imagined them gathering, pilgrims paying alms, a tour guide eulogizing.

Walking towards Washington Square Park, I phoned a man I had been referred to named Arthur. He lived at 24 Fifth Avenue, an ornate structure built directly on top of the stream. Arthur had been a tour guide in the Village, knew the neighborhood intimately. He wouldn’t meet me, preferred to speak on the phone. Just in the middle of talking about the stream, he broke off. “You know, on my tours I used to sing,” he said. “At the appropriate moments, I would burst into song.” His voice flattened. “But then I had a stroke. And now I don’t sing at all.”

Continuing towards the park after hanging up with Arthur, I recalled an article I had read about the brook from 1883. It was in the Times, a description of Viele’s presentation to the New York City Sanitary Association regarding the path of Minetta Brook. The article was for the most part a starchy recitation of facts. Towards the end, a character appeared with an almost Homeric quiver. “An old gentleman present, whose name is forgotten, arose, and in a trembling voice said: ‘I have practiced medicine for fifty years in the vicinity of Minetta Brook, and I can trace the course of the stream by my practice in intermittent fevers.’”

It was dusk in Washington Square Park. I sat on a bench, my search having come to an end. The stream could not be seen or heard, but could everywhere be felt. The sky above the park was leaden. During the Civil War, when soldiers dragged artillery through here, they turned up burial shrouds. The park had been a potter’s field, a graveyard for the city’s destitute and unknown. The anonymous corpses underfoot, the phosphate lime of their bones, seeped into the invisible stream.

Will Hunt is writing a book about subterranean space.