With Britain's prisons overflowing and outdated, coupled with predictions of a continuing rise in the number of inmates, the government has decided to build so-called "Titan jails" to help deal with the problem.
Wandsworth will cease to be the largest single prison in England and Wales
They will be bigger and more technologically advanced than previous prisons but what will they involve?
Following a review, Justice Secretary Jack Straw has announced that three Titan prisons will be built to hold 2,500 inmates each.
They will be "significantly bigger" than the largest existing single prison in England and Wales - HMP Wandsworth, which on average holds 1,461 male prisoners.
A single Titan prison would almost match the capacity of the three prisons grouped together at the Isle of Sheppey - Swaleside, Elmley and Standford Hill - which currently hold 2,224 in total.
Mr Straw told Mps the prison changes "will fulfil our commitment to provide a modernised prison system that protects the public from the most serious offenders."
He said: "Prison is and will remain the right place for the most serious offenders. Custodial sentences and therefore prison places must also be available for less serious offenders when other measures have failed or are inappropriate.
"And we must have in place a rigorous and effective framework of community penalties when they are the right course."
Recommendations from the prison review, carried out by Labour peer Lord Carter of Coles, are light on detail, skimming over construction and location, but emphasising cost and efficiencies.
Supply vs. demand
The locations of the Titans would be "as close as possible to the regions where demand for prison places outweighs the supply - notably London, the West Midlands and the North West".
But the thought of placing a large-scale secure prison in or even near densely populated London seems impossible to criminologist Dr Stephanie Eaton.
"The government will find opposition in local areas," she says.
"I'm a [Liberal Democrat] councillor at Tower Hamlets, and we can't even find room for a cemetery, so to think you could build a new prison in London, either inner or outer London, is impractical," says the senior lecturer at Kingston University.
And having large prisons in a few locations will "inevitably" lead to offenders being placed far from family, communities and jobs - all aspects that are known to encourage people not to reoffend, she adds.
"Smaller, community-based, and with access to family - that is how prisons should be."
But apart from the location, Dr Eaton objects to the thinking behind building more prison spaces as more people are sentenced to jail.
"We already lock up too many people. These prisons are not necessary. You need meaningful penalties so that the majority of offenders are not sent to prison."
Prisoner numbers are expected to rise
The Sentencing Commission has said it will look at the overall sentencing framework in relation to the prison population.
The review says that there are "some operational challenges associated with large prisons" - such as the possibility of large scale disturbance, meeting the needs of specific groups of prisoners, and managing a large number of staff.
It does not give much information about the use of technology to control riots and isolate areas of a jail - but says it will be "built in to the fabric of the building".
It also outlines the use of electronic door operation and bio-metric scanning - the use of fingerprints or iris scanning to identify people.
US examples of "super prisons" do rely heavily on such technology, but Dr Eaton calls it "unnecessary and expensive" when it compares to "old-fashioned keys".
The benefit, as she sees it, is that another human being has to unlock a door, giving the inmate some social interaction, rather than isolating them through remote control of their surroundings.
"The government has to strike a balance between security and respecting the human rights of inmates and encouraging rehabilitation," she says.
Campaign group the Howard League for Penal Reform queried the lack of detail so far about the Titan prisons, and generally the lack of consultation on the review.
Would they be like the US "super prisons", where, as league director Frances Crook says, "all murderers are locked up under very high security" or would they be like very large prisons in Brazil, where everyone is lumped together?
Spokesman Andrew Neilson said: "[The government] is trying to build its way out of a problem, but the problem is that the sentencing problems are unsustainable".
With the Titans expected to be operating from 2013, the government has said it would look at closing "ageing and inefficient" prisons.
Victorian prisons, like London's Pentonville, housing 1,100 inmates, could conceivably be closed.
It was opened in 1842 and the Prison Service says that although there has been refurbishment, the original four cellblocks are as they were 165 years ago.
Mr Neilson says the government would probably be eyeing up its prime London location, and "rather than spend money on an old, crumbling building, which probably has rats and is probably unsafe, it would prefer to build a new prison on a greenfield site.
"But the reason the prison was there in the first place was that it was close to families."
Ms Crook added: "Ultimately, Lord Carter has failed to deal with the fundamental question: what is prison for? What are prisoners meant to do all day?
"Building cavernous warehouses on greenbelt land for people to lay on their bunks all day, before being dumped into the community only to commit more crimes, neither serves the taxpayer nor past and future victims of crime."
The Titan plans have also been questioned by those who would have to work in them.
The president of the Prison Governors' Association, Paul Tidball, said: "These can only work in high population centres - or they will be the enemy of closeness to home.
"Also, small local prisons tend to be adjacent to main railway stations
facilitating easy...visits by prisoners' families and official