What subway do you take from 68th Street and 1st Avenue to 46th Street and Park Avenue?

Take the Downtown 6 train (of the 4-5-6, the dark green line) from 68th Street-Hunter College (at Lexington Avenue) to 51st Street or 42nd Street-Grand Central Station.

Then walk 1 block west to Park Avenue, and 5 blocks south or 4 blocks north to 46th Street.