“It looks good,” said Angela Medina, 20, a student who was visiting the site from New Jersey on Monday. “It’s going to look different from all the other buildings around. I’m definitely looking forward to seeing it when it’s done.”

The tower won’t open until 2013, but workers installed the first pieces of the stainless steel exterior on three corners of the 20th floor on Sunday. They then began adding glass on Monday, said Steve Coleman, spokesman for the Port Authority.

In all, the 1,776-foot skyscraper, formerly known as the Freedom Tower, will feature 12,000 glass panels, each of which is 5 feet wide and more than 13 feet tall.