Secrets of Great British CastlesEpisodes Guide

Historian Dan Jones explores the turbulent past of six of Britain's most famous strongholds, beginning by heading to the south-east of England to visit Dover Castle. He reveals that Henry II ordered its construction not only as a statement of royal power, but also out of guilt for the murder of Thomas Becket, the Archbishop of Canterbury, in 1170. Dan discovers how a vast network of tunnels was used to defend the castle, including underground barracks built during the Napoleonic Wars and a nuclear bunker created during the Cold War.

Dan Jones explores the turbulent history of the Tower of London, which is one of Britain's most famous buildings and has been a military fortress, a palace, a royal mint, a prison, a zoo and a place of execution. He reveals how one king's obsession with money led to the Tower becoming the focus of the worst Jewish massacre the country had ever seen and explains how a mob of disgruntled peasants managed to break through its defences as they sought bloody revenge for taxes they could no longer put up with.

Dan Jones explores the history of Warwick Castle, which started as a motte and bailey fort established by William the Conqueror in 1068 and was transformed into a stone fortress two centuries later by the Beauchamp family. He examines the role Guy Beauchamp played in the kidnapping and murder of one of Edward II's closest allies and descends into the castle's claustrophobic dungeon.

Dan Jones heads to Gwynedd to explore the history of Caernarfon Castle, the building of which began in 1283 on the orders of Edward I. He demonstrates how the castle's vast stone walls and strategically designed towers repelled all enemies, even the Welsh national hero Owain Glyndwr, earning itself a truly forbidding reputation, but its military importance faded at the end of the 15th century when Henry Tudor - a Welshman - made his way on to the English throne.

Perched high on a volcanic crag overlooking the River Forth, Stirling has long been one of the most strategically important castles in Britain. Guarding the gateway to the Highlands, its battle-scarred walls have witnessed savagery and chivalry, intrigue, alchemy, adultery and murder. With the aid of location filming, aerial shots and dramatic reconstructions, Dan Jones examines the history of this stronghold and relates the stories of some of the powerful characters who have owned it over the centuries.

Dan Jones explores the history of Carrickfergus Castle in Co Antrim, one of the most ancient castles in Northern Ireland and a stronghold key to understanding the tempestuous relationship between Britain and Ireland. Dan travels to Rathlin island, where he reveals how hundreds of women and children were massacred in the name of Elizabeth I, and visits the tomb of former governor Arthur Chichester, who began a new colonisation strategy using scorched earth tactics and laid waste to much of the land surrounding the town.

Edinburgh's handsome hilltop bastion is Scotland's most popular paid tourist attraction, but it also packs some formidable defences.

Dan Jones explores the history of the Welsh capital's landmark, Cardiff Castle, and discovers more about the various incarnations over the centuries.

Part-dramatised history series. In medieval England, the North was ruled from York. Dan Jones explores the history of its castle, from the Viking Jorvik and the Normans, through the dark days of the anti-Jewish pogrom and the imprisonment of the Knights Templar, to one of its most colourful inmates - the legendary highwayman Dick Turpin.