One of PA’s most visited natural wonders and for good reason, it’s a stunning underground view. Pack a sweater or hoodie, it gets chilly as you descend 125 feet. Read more.
In a suspenseful scene, which was shot at Navy Pier for "The Dark Knight", the Joker (Heath Ledger) pits two ferries full of people - one loaded with citizens, one with prisoners, against each other. Read more.