Is Trump's plan to reopen notorious Alcatraz prison realistic?

US President Donald Trump has doubled down on his proposal to reopen and expand Alcatraz, the once-notorious prison island in the icy waters of San Francisco Bay.

Alcatraz- popularly known as "the Rock" - has been closed for decades, and is now a historic landmark visited by millions of tourists each year.

The US President says he believes the prison could be once against used to house dangerous inmates, and serve as a symbol of law and order in the US.

But experts say that refurbishing the dilapidated remains of the once-formidable prison is "not realistic at all".

Here's what we know about the plan.

Located on an island about 1.25 miles (2km) offshore from San Francisco, Alcatraz was originally built as a naval defence fort, but was rebuilt in the early 20th century as a military prison.

In 1934, it was formally converted into a federal prison - Alcatraz Federal Penitentiary - housing notorious inmates including gangster Al Capone, Mickey Cohen and George "Machine Gun" Kelly, among others.

The prison was among one of the most notorious in the US at the time, and was considered inescapable because of the strong currents and frigid temperatures of San Francisco Bay.

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The facility was also made famous by the 1979 film, the American biographical prison drama, Escape from Alcatraz, which recounted a 1962 prisoner escape with Clint Eastwood starring as ringleader Frank Morris.

It was also the site of the 1996 film The Rock, starring Sean Connery and Nicolas Cage, about a former SAS captain and FBI chemist who rescue hostages from Alcatraz Island.

According to the Federal Bureau of Prisons, BOP, it was nearly three times more costly to operate than other federal institutions and was ultimately closed by Attorney General Robert Kennedy in 1963.

The island and prison are now a museum operated by the National Park Service. More than 1.4m people visit each year.

"Alcatraz is a place where the past meets the present," Christine Lehnertz, president and CEO of the Golden Gate National Parks Conservancy said in a statement sent to the BBC.

"It challenges us to listen, to learn, and to carry forward the stories that still shape our world today," she added.

Donald Trump is not the first president to mull re-opening the facility as a detention centre.

In 1981, Alcatraz was one of 14 sites considered by the Reagan administration to hold up to 20,000 refugees who had fled from Cuba to Florida in the famous "Mariel Boatlift".

The site was eventually rejected due to a complete lack of adequate facilities and its value as a historical tourist site.

In a Truth Social post on 4 May, Trump first said he had directed his government to re-open and expand the island prison, saying that "for too long America has been plagued by vicious, violent, and repeat criminal offenders".

Speaking to reporters at the White House the following day, Trump said that, in his view, Alcatraz "represents something very strong, very powerful" - law and order.

"We need law and order in this country," he said. "So we're going to look at it. Some of the people up here are going to be working very hard on that."

While he said he finds the idea "interesting", Trump also acknowledged that the prison is currently a "big hulk" that is "rusting and rotting".

"It sort of represents something that is both horrible and beautiful and strong and miserable," he said.

Trump's border czar, Tom Homan, also told reporters that Alcatraz could be "an option" for "significant public safety threats and national security threats".

"It should be on the table," he added.

Soon after Trump's comments made news around the world, justice department spokesman Chad Gilmartin said in a statement that BOP "is working towards rebuilding and opening Alcatraz to serve as a symbol of law and order".

But prison experts and historians have expressed serious doubts whether the plan is feasible.

"To be frank, at first I thought it was a joke," Hugh Hurwitz, who served as acting director of the BOP between May 2018 and August 2019, told the BBC. "It's not realistic to think you can repair it. You'd have to tear it up and start over."

Mr Hurwitz pointed to a number of issues with the facility, including buildings that are "literally falling apart", cells in which "a six-foot person can't stand up".

"There's no security upgrades. No cameras. No fencing," he added. "You can't run a prison."

"I have two words: water and sewage," said Jolene Babyak, an author and Alcatraz historian who lived there for two stints as a child with her father, a prison administrator.

"In its heyday, all the sewage for 500 or more people was just dumped in the bay," she said. "Nowadays it has to be boated off. It's just not realistic at all. But it captures everyone's imagination."

When the facility closed in 1963, the BOP said it was nearly three times more expensive to operate Alcatraz than any other federal prison - the per-capita cost being $10 and $13, compared to between $3 and $5 for other facilities. This was in part because it required food and supplies to be dropped off by boat.

In today's federal prisons, the per capita cost for inmates is between $120 and $164 - meaning that the costs could rise to over $500 per person in a facility like Alcatraz, which could only hold about 340 prisoners at its peak.

"It was mind bogglingly expensive to keep a convict there," said John Martini, a historian who spent several years on Alcatraz as a ranger with the National Park Service. "Things have not changed. But the place has gone downhill."

"It's basically a shell. Even the concrete has major problems. The Park Service has put millions into structurally stabilising it," he added. "They would need water, electricity, heat, and sanitation. None of those functions."

"This [Trump's comments] are just another twist in the odd history of Alcatraz," Mr Martini added.