There are 3 stories in the old jail. An 1886 earthquake damaged the building and the 4th floor and a tower were removed.
Open air stairs, running through a large shaft connect each floor. The entrances and other openings are barred shut.
A guess on my part is that there were some type of openings on the main stair shafts for ventilation. Growing up in an old NYC tenement I an aware of the air shafts built into buildings this age. In NYC it was law all 1800’s buildings have a shaft to prevent disease. Given the crowded cells and damp rooms I may be too kind here, after all this was an 1800’s prison where many people never left.
For a short time, starting in 2000, the American College Of Building Arts owned the jail. Some features, like the above plaster carving, were added. In a short time it was discovered there were little skills available to maintain the historic nature of the construction and the building was sold. It is now a project of the National Trust for Historic Preservation.
Because the building housed the wardens family, civil war prisoners, actual high sea pirates, and overnight innocents several different sets of stairs and entrances are available.
The different stairs and steel barred hallways meant that in pretty short order I was lost. I have no sense of direction… none.