Philadelphia, USA: Visit the prison where Brad Pitt went 'crazy'

From the outside, Eastern State Penitentiary in Philadelphia looks like a medieval castle – all forbidding grey stone, crenellated battlements, and towers that look like soldiers should be up there pouring boiling oil on their foes below.

Of course, Philadelphia isn't overly famous for its prison – people come to this vibrant city for the Liberty Bell and the cheesesteaks, among other things – but seeing as the penitentiary is an easy five-minute walk from the Philadelphia Art Museum and its Rocky steps and statue, it's worth the minimal effort it takes to visit.

Grim and foreboding (it must have been quite something to pass under these thick, 10-metre-high walls for the first time), this was the most expensive prison in the world when it opened in 1829.

It was a step up from the other prisons of the day, emphasising reform over physical punishment (though that translated to single-occupancy cells with a skylight, bed and Bible for company).

It was also famous for its radical "wagon-wheel" design whereby all the cell blocks "spokes" were controlled and visible from a central hub. For trivia buffs, that hub is where Brad Pitt went crazy in the 1995 movie 12 Monkeys.

The prison closed in 1971 and today it's a haunting ruin, a gloomily beautiful world where the outlines of the past can be seen among the peeling paint, rusted gates, decaying cellblocks and empty guard towers. It's hard to imagine that such an imposing structure – it still dominates the streets around it – was once almost terminally run down and had to be saved from redevelopment as a mall or luxury apartments.

Today, this "preserved ruin" attracts more than 220,000 visitors a year. You can tour it on your own – there's self-guided audio tour narrated by actor Steve Buscemi – or take an official tour led by a staffer. Both lead you through the history of the prison through topics such as escapes, religion, riots, sports and sexuality.

Nothing much has been done to dress up the buildings apart from making sure the roof doesn't fall in and it's all the better for not being sanitised.

We are taken around by a staff member toting a bag emblazoned with a rule from a 1960s' Handbook for Inmates. To wit "Neatly trimmed moustaches are permitted. However, the raising of a beard is prohibited."