Originally 103 towers were built between 1805
and 1812 to resist a potential invasion by Napoleon.
29 were built between Aldeburgh
and St Osyth Stone between 1808 and 1812 to protect Essex and Suffolk, the rest having been built a few years earlier across the Kent
and Sussex coasts. They were built of brick, 13 foot thick on the seaward side,
stood about 30 foot high and were equipped with a cannon on the roof. A supporting
fort, or Redoubt, was built at Harwich.The largest tower is Martello CC, at Aldeburgh, which is effectively four towers joined together.