Redevelopment of the World Trade Center site is now evident in the Lower Manhattan skyline, mostly with the under-construction One World Trade Center, now more than 90 floors up. But just across the 16-acre site, another tower—4 World Trade Center—is rising just as fast, if not as tall.

The building is slated for completion at the end of 2013, and unlike One World Trade, it’s being constructed by a private developer, Larry Silverstein. View a slide show of the progress.