Already 48 stories high, the rising steel and concrete skeleton of the World Trade Center site's Tower 1 is all but impossible to miss.
But what's easy to overlook is the first glimpse of the building's transformation from a drab construction site to a stunning, 21st century, 104-story office tower.
On Sunday, Nov. 13, crews installed the first pieces of its shiny steel-and-glass façade, on three corners and in the center of the 20th floor's eastern wall. The windows are the first to be installed anywhere on the site since the rebuilding began.
"This is another tangible sign of progress that people who walk past the site can see as we work to get this tower completed in 2013," said Steven Coleman, spokesman for the Port Authority, the building's developer.
The very first pieces of the façade were bolted on to the northeast, southeast and southwest corners of the tower's steel frame at the 20th story. Crews spent most of Monday morning and afternoon putting up the first two flat window panels near the center of the floor's eastern wall, a painstaking process that must be done with absolute precision because the rest of the installation depends on it.
"Once they get rolling, they'll be able to install glass panels at a rate of one floor per week," Coleman said.
One at a time, each steel and glass panel is wheeled to the tower's outer edge with a hand-operated forklift, lowered into place and then bolted tight to the tower's frame. Glass is added in once the steel panel is secure.
When the 1,776-foot tower is complete, crews will have placed more than 12,000 flat panels and 700 corner pieces. It will take approximately 160 panels to wrap one of the larger, lower floors in the tower, while the upper floors will need around 100 panels.
Installation of the 13-foot-high panels began on the 20th floor, Coleman said, because the Port Authority will need open access to the tower's base, containing the mechanical equipment, for several more months.
"There is a lot of equipment that still needs to be loaded onto the mechanical floors in the [base], so the glass wall must come in later," Coleman said. "Additionally, with all the activity at the base of the building now, we scheduled the wall later to minimize damage."
Coleman said installation of the prismatic glass wall on the tower's base-meant to obscure the mechanical equipment behind it-would likely begin in early 2012.