Today there is no sign that there was ever a flood. Daniels said there has been "almost indescribable" progress on construction since the storm.Structural work appears mostly complete on the glass pavilion and wide staircase and ramp visitors will use to descend into the museum, past two towering "tridents" that once helped form the distinctive base of the twin towers. Once silvery, the columns were stripped bare by the fires on 9/11 and are now the color of rusted, raw steel. From a mezzanine, patrons will be able to peer into a deep, nave-like hallway nicknamed the South Canyon. The hall's high western wall will eventually be covered with artwork that people around the world made in tribute to the victims after the attacks. Another exhibit will feature supportive notes and letters. "They continue to send things. It's amazing," Katsimatides said. "That outpouring of support is one of the things that got the 9/11 families through." Further down the ramp, visitors come to a platform overlooking an even more massive cavern bordered by the slurry wall, a 70-foot-tall, steel-studded concrete slab originally built to keep the Hudson River from flooding the trade center construction site. In the hall's center stands the last steel column removed from ground zero during the cleanup operation. Recovery workers covered the pillar with their signatures before it was carried away, and visitors will get a chance to leave their own mark on another big piece of steel near the museum's exit â¿¿ though their autographs will be captured by a computerized touch screen and projected on the slurry wall, rather than left in ink on metal. Throughout the museum, curators have hung pieces of steel that were bent and twisted into striking shapes, including one sheet of metal that now appears to ripple like a flag and a huge girder bent by the impact of the aircraft hitting the towers.