This early map of the Portrush peninsula thought to date to around 1570 shows several interesting features including a harbour (now the Old Dock), a spring (now the Medieval well in Antrim Gardens), a ruined Church Building (in the vicinity of Antrim gardens), an English Galleass and what appears to be a ditch and/or bank cut across the peninsula from the West to the East. It also shows a fortified area above the harbour on Crannagh Hill a now demolished portion of Ramore Head.
The Lord Deputy Perrot, writing from Dunluce Castle on the 17th of September, 1584, reported that he had taken Dunluce Castle, Dunferte Castle (Ballyreagh Castle) and “a pyle by Portrushe” believed to be the castle above the harbour. The ditch and/or bank cut across the peninsula was clearly intended to make the whole promontory defensive but there is no way of dating it. It is possible that it was planned by Perrot to defend Portrush after he was granted the land but it is known if it was ever constructed. If it had been Portrush would indeed have become an island!