Wander around the Brooklyn Navy Yard, and remnants of the Yard’s illustrious past practically stare you in the face—from 19th century dry docks to the Naval Hospital, active from 1838 to 1948.

But in this 300-acre complex (above in 1918) on the East River and Wallabout Bay—closed in 1966 and now a hub for more than 450 small businesses—historical relics also lie underfoot.

That’s what one Ephemeral reader found when he came across this curious manhole cover. “Y & D,” the top letters read, then “Electric Subway 1903.”

Electric subway? Is this cover a portal to a forgotten underground transit line built to move the thousands of people who worked at the yard over more than a century and a half of shipbuilding?

Not quite. “Y & D” stands for yards and docks, which referred to the Bureau of Yards & Docks, a U.S. Navy unit formed in 1842 and responsible for constructing and maintaining docks and other naval facilities.

The electric subway was actually an underground electrical conduit system installed at the Navy Yard in 1903, as the Yard upgraded its power sources from steam to electric. This effort must have been under the auspices of the Bureau of Yards & Docks, hence the initials on the cover.

It’s not the most attractive manhole cover, and it doesn’t have the artistic touch of some of the beauties found beneath your feet on Gotham’s sidewalks.

But it does tell contemporary New Yorkers about the complexity of the Navy Yard and the transition to electric power—something happening throughout the city as well.

Source: The mysterious Brooklyn manhole cover that references an electric subway