Answer: Auburn
Step-by-step explanation:
The Auburn State Prison was began to use solitary confinement in 1821 when the then warden William Brittin, introduced it after being inspired by the prison system in Pennsylvania.
The cells were stacked five tiers high and in a bid to make the inmates quite uncomfortable, had no plumbing or central heating. This made such prisons quite cheap and easy to build and led to the Auburn model being replicated for decades.