near Brooklyn Bridge Terminal
The Brooklyn Heights Railroad started in 1891 as a small cable-car company running from Brooklyn City Hall (now Borough Hall of course) along Montague St. to the Wall St. ferry at it's foot. But by the turn of the 20th century, with the help of Brooklyn Rapid Transit Company, it became the operator of almost all of the street trolley lines in Brooklyn. Many of those lines terminated at the foot of the Brooklyn Bridge, at Sands St. where this relic of the era remains today.
The large square grid pattern with raised lines and a rectangular badge in the center was a popular design from the 19th Century, used by many Brooklyn companies.
The cover was probably part of the electrical system of the trolley lines. The 19th century power sub-station for Brooklyn Rapid Transit Company can still be seen on the small stub of Sands Street extending east from Cadman Plaza near this cover.
This cover is on Cadman Plaza East a little south of the Brooklyn Bridge stairway, at the site of the former Sands St. Terminal. Other examples are found at Borough Hall Plaza and at the foot of Division St. in Williamsburg.