Tomorrow will mark the 11th anniversary of the attacks of September 11, 2001. After years of effort and numerous setbacks, three of the proposed seven towers to be built at the World Trade Center complex have "topped out," reaching their structural maximum height. Seven WTC was completed in 2006, Four WTC topped out in June of this year, and the tallest, One World Trade Center (formerly known as Freedom Tower), just topped out at 104 floors on August 30. Financial difficulties have left the future of the remaining towers in doubt, and have raised concerns about the still-incomplete National September 11 Memorial and Museum, as the foundation that runs the memorial estimates that it will cost $60 million a year to operate. Gathered below are recent images of the rebuilding at ground zero in New York City.