Did you ever want to see an animated map of how the city's subways were built? Okay, probably not, but 2nd Avenue Sagas points us to a map someone made that shows the lines in the order they were built.
Starting with the Franklin St. Shuttle, remnants of the original Brooklyn El system, and the far reaches of the J line which contain the oldest surviving transit structures still in use in the city, the map moves on to the original IRT lines before extending through time. The subways and the city literally come to life as the map unfolds its stations and tunnels.
It certainly provides an interesting look at the history of the system.