A County Longford carpenter's Florida island, built as a Celtic cross, is on the market for $12 million

Bannon Island has remained in the same Irish American family since the 1880s. Now it is listed for $12 million, and its story runs straight back to Ireland.

Bannon Island sits on Lake Marion in Polk County, Central Florida, a 23- to 24-acre private retreat reachable only by boat, seaplane, or helicopter. It is a striking address even by Florida standards, but what sets it apart from the state's other private islands is who built it and why.

The island's first known resident was Echo Emathla Chipco, known as Chief Chipco of the Seminole tribe, who kept a camp there until the 1880s. Soon after, the land was purchased for $1.25 an acre by an Irish-born Catholic carpenter named Patrick Bannon, who had settled in New York after leaving Ireland.

Bannon was reportedly skilled enough to be recruited by Thomas Edison to build phonograph cabinets. He and his wife, Annie Marie Ryan, decided to head south to Florida after Bannon suffered a bad bout of pneumonia. In 1887, he began building a two-story home on the island, giving it a shape that spoke to his roots. The house rises from an octagonal great room at its center, with four wings extending outward to form the outline of a Celtic cross.

Bannon was a skilled woodworker, and he hand-cut the cypress that lines the walls, floors, and ceilings, much of it harvested from the island itself. That cypress remains in the home today.

Five generations, one family

The island has never left the Bannon family since. Patrick Bannon's descendants, the O'Learys, have held the property through five generations, farming its citrus groves, raising children among its bobcats and alligators, and quietly maintaining the homestead their great-grandfather built by hand.

Dr. Patrick O'Leary, who owns the island and is now in his 80s, remembers visiting as a child when the island had no electricity or running water. He added his own touch to the house over the years, including a pineapple finial on the staircase newel post.

"I have a lot of memories there, and whoever buys it should work on developing theirs," O'Leary told Growth Spotter. "They can take what we have experienced, but they need to put their signature on it."

That continuity earned the island a rare distinction. The Florida Department of Agriculture has designated Bannon Island a Century Pioneer Family Farm, a title reserved for properties that have remained in the same family's hands for 100 years or more. Few private islands anywhere carry such an unbroken family history.

Inside the homestead

In the 1990s, the family brought in architect William H. Phillips, known for his work with Southern Living, to restore the original homestead. His renovation added a glass-walled orangerie that opens up panoramic views of the lake while preserving the character of Bannon's original build.

The main residence now measures 5,034 square feet and still centers on that octagonal living room, with a staircase leading up to a loft bedroom. A separate 2,698 square-foot duplex, along with four additional outbuildings, rounds out the property. One room holds the family's heirloom Steinway piano. Outside, the island is thick with native Florida forest and dotted with historic citrus groves, including Valencia orange trees planted generations ago.

Lake Marion itself is a 3,021-acre spring-fed lake known as one of Florida's premier bass fisheries, drawing anglers from across the country and hosting nationally televised fishing tournaments.

Bannon Island is a rare thing even among private islands, a piece of Florida wilderness shaped, quite literally, by an Irish immigrant's memory of home.

Check out more photos of Bannon Island here: 

For more information, check out the full listing here.