Although Marco Island’s storied history dates back centuries – the island was the domain of fierce Calusa Indian warriors, Spanish explorers and rugged pioneers – the modern era began just 44 years ago. Developers Elliott, Robert and Frank Mackle Jr. had no idea what to expect when the island “officially’’ opened its doors on January 31, 1965 but they should not have worried. Some 25,000 visitors poured onto the island to catch a glimpse of what a future Paradise would look like. Within a month, 50,000 inquiries flooded the island’s tiny sales and administration center. That was then; this is now . . . today, close to one million visitors walk through the doors of the Marco Island Marriott Beach Resort annually.