St Mawes Castle is a coastal fortification located in Cornwall, England. Built in the late 16th century under the orders of Queen Elizabeth I, it was designed to protect the Carrick Roads and the naval port of Falmouth from potential invasions by the Spanish Armada. The castle features a circular design and is made of local granite, showcasing the military architecture of its time. Today, St Mawes Castle is managed by English Heritage and is open to the public. Visitors can explore its well-preserved structure, enjoy stunning views of the surrounding coastline, and learn about its historical significance through informative displays.