Queenborough Castle is a historic fortification located in Queenborough, Kent, England. Built in 1539 under the orders of King Henry VIII, the castle was designed to protect the Medway estuary from potential invasions. Its strategic position allowed it to serve as a defensive stronghold during a time of political unrest. The castle features a unique circular design, which was innovative for its time. Although much of the structure is now in ruins, it remains an important archaeological site and a popular destination for visitors interested in English history and medieval architecture.