The castle's main entrance housed an innovation so lethal that it's been dubbed a medieval machine-gun
Caernarfon Castle will be the star attraction of BBC2's Climbing Great Buildings at 6.30pm on 8 September.
The series sees architectural historian Dr Jonathan Foyle get closer to Britain's most iconic structures than any television programme has done before.
It is only by climbing these great structures that Jonathan can reveal the secrets of our nation's best-loved buildings and tell the story of how our architecture and construction has developed over 1,000 years.
Caernarfon castle, built in 1283, is one of the most magnificent examples of medieval castle building in Britain.
Jonathan, aided by climber Lucy Creamer, tests his climbing skills to reveal the secrets of the castle's construction and what it would have been like for anyone foolhardy enough to attack it.
He scales over 100 feet on the Eagle Tower to investigate how the architect behind Caernarfon revolutionised castle building in Britain.
He discovers how the castle's design and decoration was inspired by the ancient Roman town of Constantinople.
And he tests the limits of his courage to zipwire high above the castle before abseiling down the King's Gate to investigate the fortified main entrance which housed an innovation so lethal that it's been dubbed a medieval machine-gun.
Each episode in this 15-part BBC Two Daytime series reveals a new perspective on an architectural masterpiece, ranging from St Paul's Cathedral to contemporary buildings such as the Imperial War Museum North in Manchester.
Jonathan said: "This is truly an exceptional journey for me and an amazing opportunity for viewers to see some of our finest architectural treasures in a whole new light."