Tours at the former Missouri State Penitentiary in Jefferson City have been canceled through the end of the year.
Officials with the penitentiary say due to the presence of mold in the buildings, tours will be discontinued through 2013.
The Jefferson City Convention and Visitors Bureau says the musty smell was getting unusually bad and they called the state in to begin testing.
The group is still awaiting test results, but they decided closing for the season would be the best way to proceed.
Just last week, site owners had canceled tours through Oct. 2 for "site issues."
Anyone registered for a tour will be contacted and be given a complete refund. Between 2,500 and 3,000 people will have their tickets refunded.
The Convention and Visitors Bureau says they have not started to calculate the economic loss, however, some tickets cost nearly $100, meaning losses could be in the tens of thousands of dollars.
Earlier this year, the Missouri State Penitentiary had been featured on an episode of the popular "Ghost Adventures" TV show.