the veterans memorial bridge opens up for tours two times a year - memorial day weekend and labor day weekend. the tour is self guided, and takes you through various points of the bridge - from the street car station to the open area below the street level.
the tour was really cool - great views, plus a little history lesson on the old cleveland street car system. did i mention it's free?! not only is the tour free, parking is free too! check out the official website for 2010 dates and information when it becomes available. i would highly recommend this tour - great for all ages.
http://www.cuyctyengineers.org/subway_tour.htm