For a bespectacled, peace-loving Englishman, there can be few places less congenial than a berth on the sixth floor of Miami main jail. The place has to be seen to be believed. Up to 24 inmates are crowded into a single cell, living behind metal bars on steel bunks, sharing a single shower and two toilets. Little of the bright Miami sun filters through the grilles on the windows. Visits to the yard happen twice a week for an hour. The rest of the time, inmates are holed up round the clock, eating, sleeping, and going slightly crazy. But what is most shocking is the behaviour of the inmates themselves. For reasons that remain to some extent opaque ... the incarcerated here have created a brutal gladiatorial code of fighting. They fight for respect, for food and snacks, or simply to pass the time. With around 7,000 inmates, the Miami jail system is one of the biggest in America - a so-called mega-jail". In America, jails are distinct from prisons in that they hold people who are pre-trial and therefore unconvicted. But the hardened few hundred who are either charged with particularly serious offences or have a track record of misbehaving behind bars get sent to the fifth and sixth floors of the main jail - a place with its own myth and lore.