In 1940 the Museum received a small but important collection of objects from the Bangor City Collection. These were all that remained of the Captain John Jones collection that had been donated to the City in 1870. John Jones (1798 – 1876) was a successful Liverpool master mariner who collected objects from all around the world, and set up his own museum in Bangor that was in existence in 1848. It was an idiosyncratic private collection that must have been like one of the earlier cabinet of curiosities, containing paintings, minerals, ethnographic objects, autographs, furniture and general miscellanea.
In 1909 the City Museum was moved to newly built rooms behind the new library in Ffordd Gwynedd. Visitor numbers dropped, and the Museum was kept shut during the 1920s and 1930s. In 1939 the City Council agreed to cooperate with the University who were opening their Museum to the public in the old Girls’ County School in College Road. The model of the Menai Suspension Bridge and the Four Alls inn sign on display in the museum are part of the city collection.