The holdings range from the city seal from 1268 to paintings and graphics, militaria, coins, textiles, furniture and everyday objects to material evidence of current Cologne events.

The current location is also only temporary after the historic armoury building, which has been in use since 1958, had to be vacated in 2017 due to water damage and only the adjacent Alte Wache could be used for special exhibitions.

One proposal concerned the storage of the model collection of the Cologne Cathedral; however, the plan of the archive director Konstantin Höhlbaum [de] to set up the long-overdue historical museum in the Torburg was successful.

[6] A proposal by Hansen in 1912 to house the holdings in a larger context in the Zeughaus as a central museum building could not be realised in the following years due to the World War, among other things.

In terms of time, Ewald spanned from prehistory to the present, and spatially beyond the borders of the Rhine Province, taking into account the diverse relationships with neighbouring regions.

A concept demanded by Adenauer for the reorganisation of all collections, taking into account the Rhenish Museum, dragged on – apparently also due to wrangling over competences between the directors.

[15] Ewald's basic museum concept fitted into the National Socialist, völkisch propaganda strategy, as a result of which it finally received unexpected support from the new rulers after years of pressure from Lord Mayor Adenauer – after the latter had already been dismissed from office in March 1933.

[12] Beatrix Alexander from the Stadtmuseum pointed out in 1992 that even in the permanent exhibition the presentation of recent history from 1848 to the remilitarization of the Rhineland followed the National Socialist historical perspective.

[15] A remarkable detail from this chapter of the museum are the unrealised plans for the construction of the monumental National Socialist Gauforum [de] on an area of 300,000 square metres, for which most of Cologne-Deutz would have had to give way.

[15] A historiographical study of his role over three eras is still pending;[18] In her dissertation from 2016, the cultural scientist Karin Hieke cites circumstantial evidence for a possible system-critical stance on Ewald's part; in addition to his non-partisanship, she mentions the fact that he saved the Judaica collection from destruction.

[14] The institution, now called the Rheinisches und Historisches Museum, opened on 26 June 1953, initially in the refurbished 14 rooms on 1000 square metres in Deutz and concentrated conceptually again primarily on Cologne as the metropolis of the Rhineland.

[22] The installation of the "Goldenen Vogels" (colloquially: winged car) by the artist HA Schult on the roof of the Zeughaus tower caused a sensation in 1991.

[22] A visible "rejuvenation" was achieved from 2007 onwards through the renewal of the guard concept and increased cooperation with the University of Cologne, which thus also contributes to the museum's work in terms of content – for example with guided tours.

A pair of donors, who were supported for this purpose in 2003/2004 by the deputy director Michael Euler-Schmidt [de][22] wanted to contribute 5.5 million euros and have a significant influence on the architecture.

[22] The plans were not completely abandoned even by the new director Mario Kramp, who took office in 2010; in 2011 he presented a feasibility and concept study that also assumed an extension building.

[34] Due to the impact of the coronavirus pandemic and the Russian invasion of Ukraine on the construction sector, as well as expected supply bottlenecks, the opening date was postponed several times.

The museum has almost completely abandoned the classic chronological narrative of history and instead opted for an emotionalised approach in which connections are made across epochs and "exciting stories" are told.

With bilingual panels throughout, tactile pavings, audio guides, Braille labelling on the exhibits and display cases that are wheelchair-accessible, the aim is to achieve the greatest possible accessibility.

Participatory elements, which were created during the conception phase in dialogue with parts of the public, show individual stories and memorabilia that deal with the respective questions.

Important objects were taken over from the Historical Archive of the City of Cologne, including the estate of the archbishop's seal keeper Hermann von Goch [de] (executed in 1398) and also probably the oldest Red Fahne of Germany from the Revolutions of 1848.

The stock of coins was significantly increased by the purchase from the collection of the Frankfurt numismatist Paul Joseph [de] and others, as well as by the acquisition of archaeological finds from Cologne.

[9] Due to the concept of the new museum being extended to the Rhineland, objects of rural and middle-class domestic culture from the Lower Rhine region to the Westerwald were added.

[43] During the Nazi era, the Haus der Rheinischen Heimat was supposed to be a "German folk museum in the best sense" and of "national political importance".

The museum inventory was joined by a range of Nazi literature, including several copies of Mein Kampf (even after 1945)[18] as well as other objects of different provenance, often in exchange with other institutions.

[44] In 1953, even before the move to the Zeughaus, it was possible - quite controversially discussed and after approval by the cultural and financial planning committee - to acquire the extensive portfolio work Köln wie es war by August Sander at a price of 25,000 DM.

[21] A first object from the Stadtmuseum relating to the impending Shoah entered the collection as a gift in 1965: a small Tefillin capsule that had been found in the destroyed Glockengasse synagogue on 10 November 1938 – one day after the Kristallnacht.

Examples of this are a printed kippa from the visit of Pope Benedict XVI to the Synagogen-Gemeinde Köln [de] in 2005, a German flag from the 2006 FIFA World Cup or costumes from the Cologne studios of the TV Series Lindenstraße.

Objects that Casanova, Johann von Werth and Wolfgang Niedecken owned; figurines and stage clothes, a Klingelpütz [de] cell door and a swastika flag that presumably hung in Cologne Cathedral.

In addition, stories of objects were told: that of a carpentered soapbox, that of the ten-year-old boy who found a rusty pistol from the First World War in his parents' garden.

In future, a special exhibition with objects from the depot will be shown once a year; they are to be understood as accompanying and preparatory measures towards a new staging of the Kölnisches Stadtmuseum.