Martello towers are part of older Guernsey history than bunkers. The Guernsey Martello towers where built by the British in 1778-1779. They were mostly used as lookout towers. There are 15 located around the island. A few of them have been made into museums, other have simply been blocked off. And there are still one or 2 that are open to the public, but there inst much more than empty space and pigeon poo inside. But its still quite cool to see.