It’s been several weeks since our last visit to the World Trade Center site. On our return today we were taken with the manner in which different architects handle ventilation at the site. The most obvious example are the two large vent structures that protrude from the west side of the Memorial Plaza. The concrete buildings are a necessary solution to a complicated infrastructure problem. Davis Brody Bond (now Aedas) designed a mesh mask for the concrete structures and workers were putting the finishing touches on south building today.