The was open for nearly 150 years and has been closed for more than 20.

A section of the prison that has been off limits will open to the public later this month, but not as part of a prison anymore. CBS News Chicago got an early visit.

"You're entering a site that holds nearly 150 years of history from before the Civil War until after 9/11," said Greg Peerbolte, chief executive officer of the .

These days, visits are voluntary. From 1858 until 2002, they most certainly were not.

"Striking architecture. Imposing architecture," said Peerbolte. "The prison building was designed really to kind of scare the heck out of not only the people inside of it, but the people outside of it."

Peerbolte now holds the key to the prison.

"You have 40 cells along each gallery here for a total of 640 cells," Peerbolte said as he showed off the old prison.

In pop culture, the prison was made famous by two brothers who were on a mission from God.

In the opening scene of "The Blues Brothers," a pair of correctional officers played by Tom Erhart and Fr. Gerald Walling, S.J. — the latter of whom spoke proudly of the experience years later as an acting and drama teacher at Saint Ignatius College Prep — rouse John Belushi as "Joliet" Jake Blues from a slumber and lead him to the exit. Frank Oz — of Muppets and Yoda fame, of course — portrays the correction officer who returns Jake's broken Timex digital watch and unused prophylactic.

The Joliet Correctional Center, as it was still officially called then, was the site for that scene. The movie was filmed in 1979 and released the following year, when Old Joliet was still a live, maximum-security prison.

The prison also had a famous role in a television series, where it stood in for the Fox River State Penitentiary.

"You have 'Prison Break' which is now making the rounds again on streaming," Peerbolte said. "It was filmed here in 2005."

Most of the 16-acre prison property has already been open to tours, except for the administration building — the part of the prison that used to be palatial.

"The prison was a castle, and the warden was the king," said Peerbolte. "So, not only did the warden work here, the warden lived here."

The fortress-like prison administration building with its turrets has been closed because part of it collapsed.

"We have been able to mitigate that damage, but we did lose a good portion of the administration building," Peerbolte said.

But thanks to more than $10 million in state and federal grants, tour groups can now tour the administration building and see what it was like to be a warden. The administration building features hand-carved woodwork and ornate details — including a marble fireplace believed to be original to the building.

But the interior of the building is hardly pristine — with wear and dust on the floors and fixtures and graffiti on the walls.

Peerbolte was asked what he feels when he walks through the rooms of the administration building.

"You feel sadness," he said. "You feel this was the end of the line for some people. You feel that there were innocent people in here."

But a prison immortalized in pop culture is now more accessible than ever. There are no inmates anymore — just history behind bars.

"This place has so many stories to tell us," Peerbolte said. "It's just incredibly interesting."

• Joliet