Indiana Gov. Eric Holcomb broke ground Thursday on a $1.2 billion prison in northern Indiana that will replace two others in the state's costliest building project ever.

The new Westville Correctional Facility in LaPorte County, when finished, will replace the existing facility with that name and the nearby Indiana State Prison in Michigan City.

The current Westville prison was converted more than 40 years ago from a state mental health center built in 1951, while the first bricks of the state prison were laid before the Civil War, The Times of Northwest Indiana reported.

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The 1.4 million-square-foot new prison is expected to house up to 4,200 male inmates and will provide "a modern and efficient space" for both inmates and more than 900 Indiana Department of Correction staff working there, Holcomb, a Republican, said in a news release.

"We are consolidating and building the largest correctional facility in the state with much-needed security upgrades, expanded health care and education services and an enhanced recidivism program for incarcerated individuals," Holcomb said.

The new prison due to be completed in early 2027 will include a 240-bed mental health unit, he said.

The Republican-controlled General Assembly funded the new prison in the 2021-22 and 2023-24 state budgets.