There’s a bit of a mystery surrounding New York’s One World Trade Center. For about a year, New Yorkers have reported hearing an eerie sound coming from the newly constructed building.

Rick Leventhal reports that if the wind is blowing hard enough from a particular direction, a haunting whistle can be heard.

Some say it sounds like wailing or screaming.

According to the Port Authority of New York and New Jersey, there’s no confirmation that the sound is coming from the tower itself. There are numerous other buildings on the site, most of which are still under construction.