Several major London tourist attractions could be forced to close after members of the GMB union voted to strike.
More than 900 City of London Corporation workers will walk out for 24 hours on 25 May in a dispute over pay.
Tourist spots including Tower Bridge, the Barbican, museums, gardens, parks and markets could all be hit after the workers voted to go on strike by a majority of 77%.
However, the corporation said it had already offered all full-time employees at least £2,300 extra which would address the challenges they face while ensuring a balanced budget.
It said providing the ‘inflation-matching pay increase demanded by the unions’ would result in cuts to services, including a considerable number of redundancies.
Anna Lee, GMB London region organiser, said: ‘This vote and support for strike action confirms how strongly our members feel and how this cost-of-living crisis is having such a devastating impact on them and their families.
‘This “them and us” culture within the Corporation of London has to end.
‘It is not OK for workers to be using foodbanks whilst Corporation bosses spend thousands of pounds of taxpayer's money on hospitality – while telling staff there's no money for pay.
‘Our members do not take this action lightly, but our demands for fair pay have been falling on deaf ears for months.
‘No one wants to go on strike but our members feel they are not being listened to, now they feel they have no alternative.
‘GMB calls on the City of London Corporation to properly value and respect their staff and return to the negotiating table.’