NPS planned to spend $1.5 million to replace two structures, add exhibitions, restore the roof and parade ground, and reconstruct a doorway that had been sealed in 1974. The fort was to operate every day of the week, year-round, though the NPS subsequently decided to close all national monuments in Manhattan on Sundays. The NPS expected that the fort would attract up to five million visitors a year. A ferry pier was also installed behind Castle Clinton. The fort reopened the weekend of July 4, 1986, as a visitor center and ticket office for the Statue of Liberty National Monument. Castle Clinton also began selling ferry tickets to Ellis Island in 1990, when that island's main building was converted into a museum. By 1996, the Conservancy for Historic Battery Park was raising $350,000 for a seasonal tensile structure, to be placed above the fort between April and October of each year. The conservancy wished to raise another $25 million to $30 million and convert Castle Clinton into an educational and cultural center. This was part of a $5.5 million renovation of the adjacent waterfront promenade within Battery Park, which was completed in November 2001. The Battery Park Conservancy had selected Thomas Phifer in 2001 to redesign Castle Clinton as a performing-arts center, although this redesign remained stalled for several years. 2000s to present The National Guard occupied Castle Clinton for six weeks after the September 11 attacks in 2001. Castle Clinton reopened to the public on October 22, 2001, though the ferries to the Statue of Liberty National Monument were not operating at the time. That December, the NPS erected a tent with seven body scanners at Castle Clinton, where visitors to the Statue of Liberty National Monument underwent a security screening. The facility could not handle large crowds, often resulting in waits of more than one hour. The NPS considered relocating the security-screening facilities to the nearby City Pier A in 2003 but decided against it. Although the security tent in front of Castle Clinton had been intended as a temporary measure, it remained in place for more than a decade. The security screening facilities were relocated to Ellis Island in 2013. During excavations for the nearby South Ferry station in late 2005, builders found the remains of a stone wall dating from the late 17th or 18th centuries. Workers subsequently found another wall under the site, and the