Relics of an era when famous felons occupied the old Los Angeles Hall of Justice have been exorcised in a dazzling restoration. But a single grim artifact has been preserved: the claustrophobic jail cell occupied by Charles Manson, Sirhan Sirhan and other celebrity defendants.

It’s in the basement where the county coroner once performed autopsies on Marilyn Monroe and Sen. Robert F. Kennedy in the building that also saw the trials of Bugsy Siegel and movie stars Robert Mitchum and Charlie Chaplin. Here are things to know about the old and new Hall of Justice:

A COLORFUL PAST

The Hall of Justice opened in 1926 as an all-purpose justice center, providing 17 courtrooms, 750 jail cells, a morgue and offices for law enforcement officials. Its proximity to Hollywood made it a site of famous trials and fictional movie and TV shows, including “Dragnet” and “Get Smart.” In 1949, movie star Robert Mitchum, convicted of marijuana possession, served his 60-day sentence there.

LIMOUSINE LEGENDS

Stories of famous inmates recounted by project manager Mike Samsing include Siegel having a limousine take him out to dinner from the jail. When motorcycle daredevil Evel Knievel served time on assault charges he wound up being released at the same time as 20 other men. Knievel ordered 20 limousines to transport the inmates, and the caravan backed up traffic for blocks.

BIG TRIALS

The Sirhan and Manson trials put the building on the world map. Manson’s trial in the slayings of actress Sharon Tate and six others drew a huge press corps. Members of his ragtag “family” camped on the sidewalk giving interviews and threatening to set themselves on fire if their leader was convicted.

One Manson follower, surrendered on the Hall of Justice steps surrounded by dozens of news crews. Another Manson acolyte, jailed on lesser charges, tied bed sheets together and escaped down the side of the building. He remained at large until he tried to rob a sporting goods store.

WHY RESTORATION WAS NEEDED

The 1994 Northridge earthquake caused significant damage to the building and it was declared unsafe. It remained shuttered for 20 years, deteriorating into a rat-infested shell of its former glory. The media used its parking lot as “Camp OJ” for broadcasts during the O.J. Simpson trial.

HISTORY PRESERVED

Architects specializing in historical restoration have already been visiting to see the careful blending of past and present in the 12-floor edifice restored at a cost of $231.8 million.

The dark building of ages past now has an ultramodern interior with skylights and an atrium that lets in natural light on every floor. The vaulted glass entry foyer with columns and an exquisitely gilded ceiling has been preserved along with its chandeliers and marble floors.

Wood paneled elevators were kept but have new operating systems. Marble walls were removed, cleaned and reinstalled.

A NEW LIFE

The grimy exterior of Sierra granite was painstakingly cleaned. Its new white facade matches its “sister” building, Los Angeles City Hall, across the street.

Gone are the old fashioned courtrooms with window air conditioners and the spooky coroner’s inquest and autopsy rooms in the basement.

One courtroom is preserved and a few of the clanking iron jail cells were moved to the basement where an “interpretive center” will offer exhibits on the building’s past.

The tiny cell where Manson spent more than a year has an open toilet, a sink and a hard two-person bunk bed. Neither Manson nor his predecessor in the cell, Sirhan, ever had a roommate for security reasons.

The reincarnated Hall of Justice will open in January as an office building for the district attorney and sheriff’s operations. At a recent dedication, District Attorney Jackie Lacey called the restoration “a divine work of art” and the building “a piece of living history.”