Martello Towers are small, round coastal defense structures built in the 19th century. They were designed to protect against naval attacks, particularly from the French during the Napoleonic Wars. These towers typically feature thick stone walls and a flat roof, allowing for cannons to be mounted for defense. The name "Martello" comes from a specific tower in Corsica, which was named after a local tower called "Martello." Many of these towers were constructed along the coasts of Britain, Ireland, and Canada, serving as lookout points and military installations. Today, some Martello Towers are preserved as historical sites.