The Louisiana Superdome is the signature building in the New Orleans skyline.

It's also covered in gunk.

Residue from the BP oil spill has been blamed by some for the dirty dome, while others claim it's smoke from the marsh fire doing the damage. But neither of those scenarios are true.

Doug Thornton, an executive at the Superdome, tells WWL-TV that "It's plain old mold like you'd find on your house," that's to blame for the home of the Saints looking like a pigpen.

The mold attracts dirt and pollution, and the result is a disgusting 10-acre eyesore on top of a beautiful downtown New Orleans landmark.

Tulane Green Wave football, the Sugar Bowl and the 2012 BCS National Championship game are all on the schedule this football season at the 76,468-seat dome, in addition to eight Saints games. Six Super Bowls have been played in the stadium with the 2013 Super Bowl scheduled there.

Thornton guarantees the roof will be cleaned up before the Saints home opener against the Bears on September 18. It's not gonna be cheap.

Stadium officials say the pressure washing of the Superdome will have a $90,000 price tag.

After the season, a special mold and mildew inhibitor will be added to paint on the roof in an effort keep the mold and dirt away in in the future.

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