The photo tour of 3 World Trade Center that Curbed ran last week included a photo of what look like tailpipes, but it didn’t say what they are. Can you find out? —A.

A spokesperson for 3WTC’s owner, Silverstein Properties, says the pipes are simply air vents for the mechanical floors. Having them protrude like that from the western side of the building was an aesthetic decision as much as a functional one. And now you might also noticed that they’re also sticking out of 4 World Trade Center (below), although on the east side.

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