Which city has 0 degrees of latitude and longitude?

There is not a single city in this place. The Greenwich meridian passes through the equator directly in the depths of the Gulf of Guinea or the Atlantic Ocean. The nearest land is located about 300 kilometers east or north. The same city of Libreville (capital of Gabon) is located at the equator, but has 9 degrees east longitude, and Accra (capital of Ghana) is at 6 degrees north latitude on the Greenwich meridian.