OK, I just made that up, but it may be true. I suspect this cover and the granite slab predate the dissolution of Long Island City in 1898. That's old!
Where is this gem? Hiding in plain sight at Trade Fair, at the corner of 30th and 30th.
I actually noticed the old stone first when water was poring into it during the rainy weeks. Only then did LIC jump out at me. I haven't noticed any others (not that I walk around staring at manhole covers or anything, ahem).