The Old Town Hall building in which the museum is housed is recorded in the National Heritage List for England as a designated Grade II* listed building.
 It was designed by Major Thomas Jarrett and built between 1781 and 1783, with a cupola added in 1782 to a design by Thomas Harrison.
It was extended in 1871 and 1886.
In 1910, the functions of the Town Hall were transferred to a new building in nearby Dalton Square.
The old Town Hall was converted into a museum in 1923.

The building is a two-storey structure built from sandstone ashlar, fronted by a projecting tetrastyle Tuscan portico.
The façade presents five bays with round-arched windows and, in the centre under the portico, a round-arched door at the top of a set of four steps.
The cupola surmounting the building has a square base with a second octagonal stage on the side of which is a clock face.
Above is a round drum surrounded by a rotunda of Ionic columns, capped by a dome.
The ground floor was originally open and contained an arcade housing a market for grain and butter.
The openings to the arcade were later filled with the current ground-floor windows.
The building has served a number of purposes over the years; as well as housing Lancaster's Council Chamber and subsequently the City Museum, it also housed the town court (complete with lock-ups) and branches of Barclays Bank (until 1969) and the National Westminster Bank (until 1977).
The Old Town Hall building in which the museum is housed is recorded in the National Heritage List for England as a designated Grade II* listed building.  It was designed by Major Thomas Jarrett and built between 1781 and 1783, with a cupola added in 1782 to a design by Thomas Harrison. It was extended in 1871 and 1886. In 1910, the functions of the Town Hall were transferred to a new building in nearby Dalton Square. The old Town Hall was converted into a museum in 1923.
The building is a two-storey structure built from sandstone ashlar, fronted by a projecting tetrastyle Tuscan portico. The façade presents five bays with round-arched windows and, in the centre under the portico, a round-arched door at the top of a set of four steps. The cupola surmounting the building has a square base with a second octagonal stage on the side of which is a clock face. Above is a round drum surrounded by a rotunda of Ionic columns, capped by a dome. The ground floor was originally open and contained an arcade housing a market for grain and butter. The openings to the arcade were later filled with the current ground-floor windows. The building has served a number of purposes over the years; as well as housing Lancaster's Council Chamber and subsequently the City Museum, it also housed the town court (complete with lock-ups) and branches of Barclays Bank (until 1969) and the National Westminster Bank (until 1977).
Lancaster City Museum