Spike Island (Irish: Inis Píc) is an island of 103 Acres in Cork Harbour, Ireland. Originally the site of a monastic settlement, the island is dominated by an 18th-century star fort named Fort Mitchel. The island's strategic location within the harbour meant it was used at times for defence and as a prison. Since the early 21st century the island has been developed as a heritage tourist attraction, with €5.5m investment in exhibition and visitor spaces and accompanying tourism marketing. There were in excess of 10,000 visitors to the island during the month of August 2016.