8. 42nd Street A/C/E at Port Authority
Though many wonder why the lower level of the A/C/E track was constructed under the Port Authority, as it never operated as part of the IND or IRT systems, it was used between 1959 and 1981 as the origin for the special Aqueduct Racetrack train. This transit path provided access to the Rockaway Amusement Park as well as football games at the Polo Grounds in upper Manhattan.
According to NYCSubway, the platform is on the southbound side with “one track, underneath the downtown local track on the upper level, and one side platform underneath the island platform.” By 2017, the entrances had all been sealed, except for one under a trap door on the “south end of the southbound platform,”