A deep blue, and at its center a large white seal finely engraved: Carolopolis, founded in 1670, and its Latin motto. The palmetto and the crescent belong to the South Carolina state flag, not to the city's.
The crescent comes from the caps of the Carolina militia, the palmetto from June 1776: on Sullivan's Island, Colonel Moultrie's fort of palmetto logs took the broadsides of the British fleet without breaking. The spongy wood absorbed the cannonballs; the British gave up. From that victory came the state's nickname, the Palmetto State, and the emblem the city still carries.
It was also at Charleston, at Fort Sumter, that the Civil War began in April 1861. And it was here, in 2015, that a white supremacist murdered nine worshippers at Emanuel AME Church.
The seal flies, intricate and talkative, above a city that learned liberty and denied it in the same breath, and whose flag tells only half of it.