New York City Subway chaining is a method to precisely specify locations along the New York City Subway lines. It measures distances from a fixed point, called chaining zero, following the twists and turns of the railroad line, so that the distance described is understood to be the "railroad distance," not the distance by the most direct route.

The 57th Street–Seventh Avenue station is an express station on the BMT Broadway Line of the New York City Subway. Located in Midtown Manhattan at the intersection of 57th Street and Seventh Avenue, it is served by the N and Q trains at all times, the R train at all times except late nights, and the W train on weekdays. It is directly adjacent to Carnegie Hall.