The museum houses collections of local and natural history and contains a planetarium constructed by astronomer Harry Ford in 1984.

[1] The museum was opened in April 1981 in a Grade II listed building that was previously Southend's first free public library.

The library service had moved to a new purpose built site on Victoria Avenue, which opened on 20 March 1974.

[5] In September 2018 the museum opened a major exhibition of finds recovered from the wreck of the HMS London, a 17th Century Cromwellian era warship that exploded and sank in the Thames Estuary in 1665.

The excavations unearthed a number of Anglo-Saxon artefacts that suggested a high-status burial; carbon dating has revealed that the burial probably dates from about 580 AD, and may have been the tomb of Sæxa, brother of Sæberht, King of Essex.