The Berlin Fortress was the fortification of the historic city of Berlin. Construction started in 1650. The ramparts, walls, moats and glacis of the 17th-century bastion fort ran around the historic city limits. The demolition of its ramparts began in 1740.

Frederick William was Elector of Brandenburg and Duke of Prussia, thus ruler of Brandenburg-Prussia, from 1640 until his death in 1688. A member of the House of Hohenzollern, he is popularly known as "the Great Elector" because of his military and political achievements. Frederick William was a staunch pillar of the Calvinist faith, associated with the rising commercial class. He saw the importance of trade and promoted it vigorously. His shrewd domestic reforms gave Prussia a strong position in the post-Westphalian political order of Northern-Central Europe, setting Prussia up for elevation from duchy to kingdom, achieved under his son and successor.