It sat on the eastern side of an open triangular area, which still exists today: the Schlossplatz (which translates into English as "Castle Square", whatever its shape might be).

In 1585, they constructed a palace (known as "the long building by the water", German: der lange Bau am Wasser) on the northern side of the Schlossplatz, complete with water-mill and library.

The architect was Jonas Erikson Sundahl, whose design was in the modern Late Baroque style - for show and comfort, and not for defence.

The site was marshy, so preliminary work involved driving very many oak piles into the ground to provide a solid foundation.

Christian IV, Duke of Zweibrücken 1735–1775, entertained notable creative artists at his palace, including the leading operatic composer Christoph Willibald von Gluck.

On 14 March 1945, in the final stages of World War II, Zweibrücken was the target of an Allied bombing raid.