Fred takes a look at the 11th-century building programme undertaken by the Normans which resulted in mighty fortress cathedrals like Ely and Peterborough.

At Peterborough Cathedral, Fred reveals the secret weapon the Norman builders had at their disposal - the stone arch - and demonstrates just how the early stonemasons constructed them. At Ely, Fred climbs high up inside the building to examine the alterations and additions made by later builders. Inspecting this construction masterpiece sees Fred scaling rooftop ladders to examine the incredible octagonal lantern built in the 14th century, an amazing feat of early engineering. Fred also has the lowdown on exactly how this feat was accomplished.

Fred's final destination is Rochester, this time to examine a Norman castle rather than a cathedral. Here, he demonstrates how the tactics used all those centuries ago by attackers to try and destroy tall towers bear a startling resemblance to the way he used to pull down tall buildings.

Fred Dibnah's Building of Britain continues with the famous steeplejack investigating one of the greatest feats of royal engineering - the constuction of the great chain of castles on the coast of north Wales. Travelling to Harlech, Caernarfon and Beaumaris, Fred reveals the building techniques and revolutionary defensive features that helped Edward I subdue the rebellious Welsh. Fred also charts the achievements of the king's architect Master James of St Georges, a Frenchman who revolutionised castle design in England.

In his mission to uncover the craft and engineering skills that helped to build Britain, Fred looks to the Middle Ages and the transformation of an Englishman's castle into his home.

Carpenters were the great engineers of this time, and Fred visits Stokesey Castle, the oldest moated and fortified house in England, to scale the walls and examine the technique of 'jettying' - making the bedroom a bit bigger. Fred also discovers how massive arched timber roofs were constructed.

At Little Moreton Hall in Cheshire, Fred explores one of the finest examples of timber-framed architecture in England and demonstrates how carpenters of the 15th and 16th century actually constructed these chocolate-box buildings. Fred's journey ends at Harvington Hall near Kidderminster, home to some of finest priest holes in the country, devised by master carpenter Nicholas Owen during the reign of Elizabeth I.

Fred Dibnah's search to discover how the work of the builders and engineers of the past helped to shape Britain brings him close to his home town of Bolton, where the mid-18th century saw the building of the first canals and the arrival of the first civil engineers. He travels to Worsley in Lancashire to see where it all started - the labyrinth of 52 miles of underground waterways that carried coal from the Duke of Bridgewater's mines to the canal. Back in his garden, he shows us how the early canal engineers actually went about digging the cut for a canal and making it watertight. He takes a canal boat on the 127-mile-long Leeds-Liverpool Canal, and demonstrates the back-breaking labour and enginering skills that went into building the tunnel that takes it under the highest point on his route.

n the final programme of the series uncovering the construction and engineering skills that went into the building of Britain, Fred Dibnah indulges his personal passion for the achievements of the builders of the 19th century.

Fred's final stop on this epic journey sees him scaling the heights again, this time inside the Westminster clock tower - the one we call Big Ben - where he reveals what makes the country's best-known clock tick to time and how the huge bell was originally constructed.