Thousands of people waving Union Jacks crammed Gibraltar's centre to mark the colony¿s National Day and rejected any transferal of sovereignty to Spain.
The demonstrators numbered an estimated 9,000 residents.
The turnout underscored the strong sentiment in favour of preserving British rule ahead of a November 7 referendum on the future of the Rock called by Gibraltar's government.
Both Spain and Britain, which are negotiating over the colony's future, have rejected the validity of the referendum.
Chief Minister Peter Caruana accused Spain of hypocrisy for claiming Gibraltar while refusing to relinquish control of Ceuta and Melilla, two Spanish North African city-enclaves wanted by Morocco.
After the latest round of negotiations began last year, Britain said it is prepared to share sovereignty, but only if Gibraltar residents approve it in a referendum to be set by the British government.
Spain ceded Gibraltar to Britain in the 1713 Treaty of Utrecht but has been attempting to recover it ever since.
AP