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Fun (read: depressing) fact, there are 2.2 million individuals incarcerated in various federal, state and county prisons around the United States, the country with the highest incarceration rate in the world (about 0.7% of its population). This number is somewhat maligned due to the fact that the United States hands out some of the lengthiest sentences when compared to similar countries, but what this really means is that incarceration is big business.
Someone has to feed and transport these inmates. Other people have to ensure healthcare. And of course, a team of architects and engineers have to build the prison. It's not as simple as building some walls and a roof and throwing a bunch of felons in it. Despite being stupid enough to lead a criminal life (or stupid enough to get caught, if that's how you want to look at it), criminals are some of the most enterprising individuals in the modern workforce. They're not willing to take 'no' for an answer, they're willing to think outside of the box for a solution, and in an unfortunate number of instances they have the conviction to cross legal and ethical boundaries to get the job done.
Hollywood has a way of making it seems as though escaping is as simple as some combination of running, digging, crawling and hiding. Right George Clooney? Right Tim Robbins? Right Clint Eastwood?
 But it's never quite how Hollywood portrays it, and it's up to the architects and structural engineers to conceive of every possible prison infrastructure flaw which an inmate can use to his or her advantage. And since those Martha Stewart blue-collar prisons are boring, and perhaps better than your desk job, let's take a look at how designers keep the crud behind bars.
The Cell
First of all, it's been years since prisons have been constructed with bars. While some are still in use, full-sized steel doors are preferred. It prevents corrections officers from being grabbed or having things thrown at them. And while it's a cliché for an inmate to obtain a file by it being baked into a cake, hacksaws and other filing implements have been used, even recently, to shear bars and foundation. The locks to the door are wired to a central hub, meaning that officers are not in danger of losing physical keys. And the locks used are often custom engineered using computerized  milling techniques. It's also become common practice to install windows in cells that are very thin and at the top of the cell wall. This way, inmates cannot see other parts of the prison, the ground, or anything else which they could use to determine orientation.
With the exception of a toilet and sink, cell furniture is made out of poured concrete. This makes it nearly impossible to break or move. Plumbing components, such as those made by Acorn Engineering, are manufactured of heavy-gage stainless steel which has a working load of 2,500 lb. The fixtures are made via seamless welding so there are no crevices to hide contraband.
To escape directly from the cell, prisons often opt for tunneling. Many newer prisons use precast concrete for exterior walls. Whenever possible, chases made for piping and HVAC run vertically, so even if the inmate found the hollow part of the wall and tunneled through, he or she can only go up or down. If at all possible, cells are located away from exterior walls altogether.
The Prison
First, prisons are almost always arranged in a campus-like, decentralized pattern. Each cell block will have its own set of showers, recreation areas, and dining halls. Even if a prison riot were to break out, it makes it much more likely to include only a fraction of the prison population. (Side note: some American universities constructed in the 1960s and 1970s also utilize this design method.)
 Wide floor plans in cell blocks offer favorable visibility to guards, and in the event guards need to physically intervene they ensure that a group of them does not become overwhelmed in a close-quarters melee. Many designs up until he 1990s were inspired by Panopticon, which was a circular prison envisioned by Jeremy Bentham way back in 1786. Many cells would be placed around the perimeter of the circle, and a central guard tower would offer sightlines into each cell. The inmates wouldn't be able to definitely tell they were being watched. Cuba's Presidio Modelo was the closest rendition to Panopticon ever constructed, but many prisons utilized an elevated guard station so one or two guards could keep an active watch on dozens of inmates. Once surveillance cameras became a practical solution, such guard stations became less important.
Outside of the prison, 12-feet-high electric fences topped with razor wire guard the prison perimeter. Interspaced with the fence are watch towers, as well as one or two gates. Most of the electric fences are simply uncomfortable to the touch, but others  are known as "stun lethal" fences and once a person touches to fence a second time the fence electrifies the individual. The fences may be equipped with vibration monitors to alert guards in nearby towers. Since the threat of being sprung from the outside can be as menacing as a break out, anti-collision rails and bulletproof panels can be placed along the fence as well. Don't forget, many high security prisons are placed in adverse locations. The three men who escaped Alcatraz are believed to have drowned in San Francisco Bay. Florence ADX, the United States' highest security level prison which hosts 9/11 terrorists, the Unabomber, and treasonists, is located in an unincorporated area of the Rocky Mountains. Even if a prisoner gets past the fence, they're not free yet.
There are many design considerations for modern high-security prisons. There used to be a TV show on Fox called Prison Break in which a structural engineer uses his knowledge to spring his brother from jail. If we were to build a CR4 penitentiary, who would be in it? And how long it would take some of our users to burrow out?
Resources
LA Times - Prison design faces judgement
Wikipedia - Panopticon
Betafence USA - Modular Security Fencing
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