Originally a private mansion built for German-American millionaire George Boldt, it is now maintained by the Thousand Islands Bridge Authority as a tourist attraction.

In 1900, George Boldt launched an ambitious construction campaign to build a huge masonry structure, one of the largest private homes in the United States.

Equally distinctive is a huge yacht house on neighboring Wellesley Island, where the Boldts had another summer home and a vast estate, incorporating farms, canals, a golf course, tennis courts, stables, and a polo field.

In the five decades after acquiring the property, the Thousand Islands Bridge Authority spent around $15 million for restoration and improvements with work continuing annually.

Improvements have surpassed that goal, as a stained glass dome, marble floor, grand staircase woodwork, butler's pantry, servant's dining room and kitchen were restored.

Most of the rooms on the third and fourth floors are unfurnished, but there are exhibits of pictures and original artifacts of the Thousand Islands region during the Gilded Age in which the Boldts lived.

Rooms are also left unfurnished to give the visitor an opportunity to imagine what the castle looked like before the Thousand Island Bridge Authority's restoration efforts.

[3] This unique structure sits on the south side of the island facing Alexandria Bay, and boasts a two-lane bowling alley and stage for performances.