There are probably 10,000 access covers like this one in Brooklyn and New York. Unmarked, but judging from the old fashioned Ships Wheel seating this cover probably dates to the late 19th century, before or just after consolidation.
A classical, unpreposessing design with 6 hexagons merging into the outer rim.
Unmarked, but the honeycomb design came to be used almost exclusively sewer openings.
This cover is on Flatbush Ave near Grand Army Plaza, but could be anywhere in the five boroughs.