The first sandstone structure to be completed at
As the threat of attack diminished over time, the blockhouse was converted from its defensive purpose into the post's prison. Instead of being used to keep people out of the fort, the blockhouse was instead used to keep people in. For that purpose, the tunnel was partially filled in and converted into solitary confinement. Moreover, rifle loopholes were filled in to prevent soldiers from passing libations to the prisoners passing the time.
Today, the blockhouse is the only sandstone building that has been completely rebuilt, though it has been located on its original foundation.