The 200-hectare (490-acre) island stands several hundred metres offshore immediately northeast of the town and is a geographical novelty in that it is accessible at low tide by a wide gravel bar suitable for vehicular travel.

Ministers Island became famous in the last decade of the nineteenth century as the summer home of Sir William Van Horne, the president of the Canadian Pacific Railway.

By the time of Van Horne's death in 1915, the island had been transformed into a small Xanadu, sporting a sandstone mansion furnished in the most lavish late Edwardian manner, manicured grounds, scenic roads, greenhouses turning out exotic fruits and vegetables, as well as a breeding farm producing prize-winning Clydesdale horses and Lakenvelder cattle.

[1] Consquamcook or Quanoscumcook Island had been inhabited by Passamaquoddy centuries earlier, traces of their occupation evidenced by the presence of shell middens.

[2] Today the Ministers Island Pre-Columbian ("pre-contact") shell middens are designated as a National Historic Site and commemorated by a cairn.

Between 1892 and 1901, Van Horne continued to expand, making two major additions to the house, with an eventual floor space of 10,000 square feet.

Van Horne was assisted in these renovations by Edward Maxwell, celebrated Montreal architect responsible for many renowned designs across Canada, including numerous CPR commissions such as the Chateau Frontenac.

The varying stages of construction created unique features, including the three roof pitches arranged serially, numerous staircases, unusual connections between rooms, and multi-levelled attics.

As an avid and knowledgeable antique collector, the walls of Covenhoven were hung with an approximate eighty works of art, many of which were completed by Van Horne himself.

This barn was used for breeding of Van Horne's prizewinning Clydesdale horses and Dutch Belted cattle, one of the only such herds in North America.

The produce of the farm and gardens was shipped to Montreal by night train during the winter months, providing the family with fresh food throughout the year.

An expert gardener, Van Horne's grounds became famous for their extensive parterres of flowers and orchards, and miles of manicured roads that bordered the island.

From there it was managed by the Royal Trust Company of Montreal on behalf of the Edith Bruce, wife of Adaline's deceased brother, Richard Benedict Van Horne, and his granddaughter Beverley Ann, born in 1932.

Throughout the forties and fifties, Mrs. Bruce made continual requests for cost-saving measures, resulting in the gardens and greenhouse operations being scaled back considerably; tenants were eventually found to occupy the property for the summers of about 1949–1953.