Visitor attractions operated by Bath and North East Somerset Council (BANES) generated a year-to-date surplus of more than £4.2m between October and December 2010.
Profit from sites such as the Roman Baths and the Fashion Museum will allow the council to invest in improvements to the attractions, as well as in protecting frontline services.
According to BANES, its programme of improvements - including a £5.5m investment in the Roman Baths - has helped contribute to the surplus.
BANES leader Francine Haeberling said: "Surpluses made at our heritage attractions are reinvested as part of our annual budget setting process into priority frontline public services.
"This surplus is also used to enhance the offer the city has to tourists so people keep on coming back, such as the new café that is due to be opened by Heritage Services in Abbey Churchyard opposite the Roman Baths in winter 2011."
