The Tribute Center isn't the "official" Museum, it is the center run by survivors, family and friends of victims located across the street, next to the rebuilt St. Nicholas National Shrine Greek Orthodox Church and right next door to the FDNY station. It isn't huge, but still has a enough items and videos to be interesting and moving. I went with my 15 year old son using our CitySightseeing Pass, and paid an additional $10 each to listen to the two volunteers tell their stories during a tour on an extremely cold and bitterly windy day, and it was well worth it.