It's really indescribable, so you must go see it for yourself! The fact that man created this massive piece of machinery that float in space --yes, this fact alone is amazing! But then to witness the miracle yourself is unforgettable. Being up close to see the immense size of the shuttle is something you will always remember.
Picture from: http://www.nasa.gov/centers/dryden/news/newsphotos/2012/endeavour_exhibit_go.html