Pleinmont Observation Tower

Tower in Guernsey

Worth seeking out if you're a military history buff, this five-storey tower was built as part of the Nazi fortifications, designed to turn the Channel Islands into impregnable fortresses. Inside there are detailed descriptions and maps of the Islands' military defences, as well as a mounted machine gun and field telephones. Clamber up the ladder to the roof for 360-degree views of the sea and countryside.