Savannah is the oldest city in the United States, state, Georgia. Savannah was the capital of the Province of Georgia and later became the first capital of Georgia. It is very rich in history, being a strategic port city during the American Revolution and a city that ran off the backs of slaves for decades. (wiki)

"We sailed from hence for Georgia, and I was glad when we got there, though I had not much reason to like the place from my last adventure in Savannah" (Equiano Ch. 7)

As aforementioned, Savannah being the first city in one of the 13 colonies, profited greatly from slavery, which is what Equiano is referring to in this line.