With England under threat of invasion, these 'Martello' towers were built all along the shores of Southern and Southeast England. Filmed at the Slaughden Martello Tower in Aldeburgh, Suffolk, England, one of 74 Martellos built in England between 1804-1814 as part of the British preparations for a potential invasion by Napoleon. Towers like them can be found all over the world - from Canada to Australia, from Malta to St. Helena. They represent an age-old debate between coastal defences and faith in the 'wooden walls' of naval power.