In 2001, the museum opened the Sackler Center for Arts Education to the public, which was another part of Wright's original design for the building, through a gift of the Mortimer D. Sackler family. Located just below the large rotunda, this 8,200-square-foot education facility provides classes and lectures about the visual and performing arts and opportunities to interact with the museum's collections and special exhibitions through its labs, exhibition spaces, conference rooms and the Peter B. Lewis Theater. Between September 2005 and July 2008, the Guggenheim Museum underwent a significant exterior restoration to repair cracks and modernize systems and exterior details. Artist Jenny Holzer painted a tribute, "For the Guggenheim", in honor of Peter B. Lewis, a major benefactor in the restoration project. The museum was registered as a National Historic Landmark on October 6, 2008.