At Ferry Reach, on the north of Castle Harbour (an area now separated by the Causeway), "Burnt Point Fort", or "Ferry Point Battery" (1688), and "Ferry Island Fort" (1790s) were built, and, much later, in 1822, a Martello Tower. The island chain across the south of Castle Harbour is often referred to as the "Castle Islands". Their fortifications are the oldest surviving English New World fortifications (due primarily to their having been constructed of stone, whereas contemporary English fortifications on the North American continent were built from timber and earth). They were also the first English coastal fortifications in the New World. As a result of their historical significance, they have been made a UNESCO World Heritage Site, together with St. George's Town.