The headquarters of the Sicherheitspolizei (SiPo), an agency of the SS, led by Herbert Kappler, were established there from 11 September 1943 and occupied the building until the German retreat from Rome.

In January 1944 all windows were walled up to facilitate imprisonment, interrogations and torture of some of the most important figures of the Italian resistance, with an estimated 2000 people passing through the building.

[2] Following donation of the apartments occupied by the SS to the Italian State in 1950 the museum was established to record the period of German occupation and Rome's subsequent liberation.

In addition to recording the torture that took place on the site, it details the persecution of Rome's Jews, with copies of newspaper reports and posters imposing bans and anti-Jewish orders.

In some of the cells writings in pencil on the plaster and other graffiti provide touching messages of life and freedom, often written by prisoners nearing death.

[3][5] In addition to the reception area the ground floor has a conference room and a library, which is particularly devoted to the resistance and contains a large number of rare pamphlets and newspapers related to the period.

It contains the white flag used by Roman officials in negotiating an ”open city” status with Marshal Kesselring, commander of the German forces in Italy.