Port Royal was originally a small fishing village on the western end of the Palisadoes that covered the mouth of the entrance to Kingston Harbour. Developed by the Spanish as a harbour, it came under British control from 1655. The site has twice been severely damaged by earthquakes in 1692 and 1907. The Royal Navy steadily developed facilities at Port Royal and by the start of the 19th Century there was a victualing yard, storage facilities, a naval hospital and careening wharves.
The map shown in the images is from about 1774 and clearly shows the location of Port Royal which was the Royal Naval Base. At this time there were limited defences on the west side of the anchorage apart from the marked Fort Augusta and a battery on what was Salt Pond Hill, now renamed Clarence Hill. Image from “The history of Jamaica illustrated with copper plates [Anon]. Credit: Wellcome Collection. Attribution 4.0 International (CC BY 4.0)”