The building of the Historical Archives is located in the northwest part of the Fortress. It was built in 1890 to accommodate the Cartography department of the Serbian army, and at a later date, the First School for Non-commissioned Officers was established in it. In WWI, the Bulgarian occupational army converted it into a prison for captured insurgents and patriots, who were taken from there to the ditch inside the Fortress to be executed by firing squad. Between the two world wars, it was used as a barracks.

It is a ground-level structure with a rectangular layout whose architecture has no clearly defined style, and in that sense it is similar to the military structures which were built in Europe at that time. It has a symmetrical form. The façade is divided by rustic semi-columns and cornices, and the walls contain a horizontal pointing in mortar, while the window frames have a shallow profile.  

The army retreated from the Fortress in 1959, when the entire complex was proclaimed to be a cultural monument. Since then, the Historical Archive started working in this building. It is an extremely significant archive repository in this part of Serbia, with very valuable documents relating to the period between the 18^th and 20^th century.

The complete reconstruction of the building was executed in phases between 2002 and 2007. During the renovation of the façade, a new representative main entrance was formed and new work and storage spaces were created, as well as an exhibition gallery, and an entirely new security system was introduced.