The museum is built directly over the top of the Chichester's Roman Bath House complex which are displayed in the ground-floor gallery.

The museum was initially located in the Royal West Sussex Hospital, and the collection was formed from donations from the general public.

The Museum was later relocated to 45 South Street after plans for a move to 7 North Pallant were abandoned due to financial difficulty.

Finally in 1936 a two-week exhibition was displayed in the Guildhall, Priory Park using artefacts that had been collected over the previous three years.

At that time the site was scheduled to become a multi-storey car park, the construction of which would have meant the complete destruction of all archaeological layers.

[7] In 2019 A bust of King Charles I by Hubert Le Sueur that was originally located on the Chichester Cross was loaned to the museum.