The Spandau Citadel with its bastions, ramparts and casemates is one of the most important and best-preserved Renaissance fortresses in northern Europe. Elector Joachim II of Brandenburg had it built in the 16th century by Italian master builders.

Of the medieval castle, the Julius Tower from the 13th century and the Palas from the 15th century have been preserved. From the 16th to the 19th century, important military buildings were erected on the large area. Today, they house museums with historical exhibitions as well as the Centre for Contemporary Art, which opened in 2018 and presents major art exhibitions.

The history of the castle and citadel is made vivid by models, maps and weapons in the Commandant's House. In the Archaeological Window, uncovered soil finds from the early days of the castle as well as a unique collection of medieval Jewish gravestones can be viewed.

In the Armoury, built in 1856, the Museum of City History uses many objects from its collection to tell the story of Spandau families, trade and military. The permanent exhibition "Unveiled. Berlin and its Monuments" in the former Provisions Magazine shows monuments that once shaped Berlin's cityscape and were often taken down for political reasons - from the Brandenburg-Prussian rulers of the imperial-era Victory Avenue to the monumental head of the Lenin Monument.