Underground.

No trip to NYC would be complete without some time spent on the subway.  A. and I spent most of our days walking.  But we did have a few opportunities - with M. leading the way - to travel the underground.

I've managed to learn and use other city's (and counries' for that matter) trains just fine, but have yet to fully grasp New York's.  It'll be my and A.'s personal mission during our next visit to conquer this intricate, VAST, and seemingly complex subway system.  Mark our word.