If you’re going to complete this quest, bring a GPS tracker or have a damn good internal compass. Comb the southern area of Central Park and keep your eyes to the ground. Look for a rocky area and then scan the surfaces for an unnatural addition.Connect the dots correctly, you’ll find a certain unmarked relic of which few are aware.The discovery itself isn’t much to see. It’s merely a bolt — a long, jagged piece of metal that was battered into the ground some 200 years ago.But it’s one of the last vestiges of lost New York that lives in plain sight without an official plaque highlighting its existence. And it’s become a popular treasure hunt for New York history enthusiasts and surveying hobbyists alike, a group of people who prefer not to divulge their knowledge of the relics’ precise locations.
Source: The Hidden Bolts that Drive Manhattan’s Infrastructure Nerds Nuts | Atlas Obscura