Watch How London Was Built online: Episode 4 Tall Buildings

Adam joins student barristers for a meal at Middle Temple Hall, one of London's ancient Inns of Court. They may have passed their exams, but until they've eaten 12 dinners here, they can't be called to the bar. The Hall was built by leading craftsmen in the sixteenth century, with a double-hammered beam roof and an elaborately carved 23-foot screen. The iron spikes on top were a later addition, following an incident of misbehaviour by students. Adam goes on to Ede and Ravenscroft, London's oldest tailor, which has catered for the legal profession for 300 years. He tries on different forms of legal dress and finds out how the wigs and robes have evolved over time. Next Adam pays a visit to the Central Criminal Court, which came to be known as the ‘Old Bailey’ because of its situation directly inside the old city gates. A ‘bailey’ is a fortified wall in a castle, and Adam can see the remains of the Roman wall in the basement. There has been a courtroom on the site since medieval times, but the current one was built in 1907, the design mirroring the nearby dome of St Paul's. Adam takes his turn in the witness box with its canopy, a reminder of the days when court was held in the open air and witnesses had to be protected from the odd shower. He also follows the path of condemned prisoners along the narrowing passageway ‘Deadman's Walk’, in the shadow of the only remaining wall of the notorious Newgate Prison. We find out a bit more about prison design at the Eastern State Penitentiary in Philadelphia. It was the first prison in the world to implement what came to be known as ‘the separate system’, which aimed not just to punish, but to move the prisoner towards spiritual reflection and change. This was done using isolation and labour. Adam visits Pentonville Prison, London that was built according to the same principles. He discovers how inmates were held in single cells, hooded and forbidden to talk to one another. Pentonville became a model for British jails and a further 54 were built to the same design in the next six years, including Australia's largest penal colony, Port Arthur.

click here to see where to watch or .