Advertisement turn_ad_publisher = 1356122; turn_ad_publisher_ad_code = 1356140; turn_ad_layout = "300x250"; turn_ad_color_schema = "DEFAULT"; turn_ad_publisher_channel = 1356129; Filming for the movie "National Treasure: Book of Secrets" began at Mount Rushmore on April 20 and was originally scheduled to wrap up after a few days. But the crew was still at work Wednesday and another week of filming was likely, said Michael Singer, unit publicist for the movie. Cold, rainy weather interrupted the filming, he said, and the director and producers have decided to take advantage of the Black Hills beauty. Some scenes that would have been set in another location were changed so they could be shot in the Black Hills. "Certain scenes that already existed (in the screenplay) were reconfigured to take advantage of the extraordinary beauty of the Black Hills," Singer said. The Mount Rushmore carving plays a key role in the new film, a sequel to 2004's "National Treasure." In this film, Nicolas Cage returns as treasure hunter Ben Gates who's trying to uncover the truth behind the 1865 assassination of President Abraham Lincoln. Crews have reportedly been shooting in several of the public areas at Mount Rushmore as well as the Hall of Records behind the memorial, near Sylvan Lake and at the Breezy Point Picnic Area just west of Mount Rushmore.