There was a Republic of Cartagena from 1812-1814 (Cartagena de Indias). Cartagena declared independence from Spain in 1811 and was recaptured by the Spanish in 1815. Later, Cartagena became part of Colombia.

I've sailed into Cartagena harbor, and the fortifications are still impressive. The most visible landmark when you're approaching from the sea, however, is the Palace of the Inquisition.

Bolivar used Cartagena as a base during the liberation of Venezuela.