The Missouri State Penitentiary in Jefferson City will reopen for partial tours in late April.
The tours were canceled in fall 2013 due to the presence of mold in the buildings.
ABC 17 News investigated the mold problem back in January, looking through inspection reports to find that the problem had dated back years.
While repairs and cleanup continues, the MSP will open Housing Units 1 and 4 and the gas chamber for history tours.
Work on the building is estimated to be completed by the end of June, and full tours are scheduled to begin in early July.