Three Democratic presidential hopefuls discussed prison reform for formerly incarcerated people at a candidate forum held at the United States’ first penitentiary.

Sens. Cory Booker and Kamala Harris, along with billionaire Tom Steyer, all took questions from the formerly incarcerated on how they would change the nation's criminal justice system. The event took place at the former Eastern State Penitentiary in Philadelphia.

Harris said that she would ban solitary confinement as a punishment if she was elected president. Her plan also includes sentencing reform, legalizing marijuana and ending for-profit-prisons.

“There are a lot of people making money off this prison system and this system of incarceration,” Harris said.

Harris and Booker have their difference on the First Step Act - a package of criminal justice reform signed into law by President Donald Trump late last year. Booker partially authored the bill. Harris said that she thinks it doesn’t go far enough.

“It's a fine first step…but that's like saying you just took a first step but now you need to learn how to walk. We need…like the plan for Step 10,” Harris said.

Booker said that the nation lacks empathy when it comes to those who are incarcerated.

“So, I don't care what it's going to take. When there are people in shackles, when there are people behind bars, that don't belong there, I don't care, I am going to fight for their liberty,” he said.

Booker said that he also supports legalizing marijuana but warns Wall Street will be ready to profit once the product is legalized.

“The revenues we're going to make as a government, the billions of dollars that are coming from the tax revenue should be invested in those communities that have been disproportionately harmed by marijuana enforcement,” Booker said.

Harris also said that people who commit crimes should be punished, but that there should be a way for them to enter back into society later.

“When one human being hurts or harms another human being, there should be consequences and accountability. But we also need to allow people - after that consequence and accountability has been paid - we need to allow people a way to earn their way back,” she said.

Eastern State Penitentiary was in operation from 1829 until the 1970s. The prison is now a historical landmark and tourist attraction. During Halloween time, the “Terror Behind the Walls” haunted attraction is held at the prison. That attraction was closed Monday for the candidate’s forum.