Upnor Castle

Upnor Castle is an Elizabethan artillery fort located on the west bank of the River Medway in Kent. It is in the village of Upnor, opposite and a short distance downriver from the Chatham Dockyard, at one time a key naval facility. The fort was intended to protect both the dockyard and ships of the Royal Navy anchored in the Medway. It was constructed between 1559–67 on the orders of Elizabeth I, during a period of tension with Spain and other European powers. The castle consists of a two-storeyed main building protected by a curtain wall and towers, with a triangular gun platform projecting into the river. It was garrisoned by about 80 men with a peak armament of around 20 cannon of various calibres.

• http://en.wikipedia.org/wiki/Upnor Castle