George Boldt ordered construction halted in 1904 when his wife Louise died, leaving 300 workers to abandon Heart Island mid-project. The six-story Rhineland castle remained unfinished for 73 years until the Thousand Islands Bridge Authority acquired the property in 1977 and opened it to revenue-generating tours. What visitors see today is a restoration funded entirely by admission fees and donations, with no tax dollars involved. The stone façade, turrets, and powerhouse complex now welcome 125,000 annual visitors who arrive exclusively by water. The 1000 Islands Boldt Castle Scenic Cruise departs from three Canadian ports—Gananoque, Ivy Lea, and Brockville—and navigates the U.S.-Canada border channels that fracture the St. Lawrence River into 1,864 charted islands. The archipelago was carved by retreating glaciers 12,000 years ago, leaving exposed Precambrian granite and a shipping lane that required dynamite blasting in the 1950s to accommodate freighters. Cruise vessels pass Zavikon Island, where a footbridge purportedly spans the international boundary, and Dark Island's Singer Castle, a second Gilded Age estate built by the sewing machine magnate's heir. Captains narrate the geology, smuggling history, and summer estate architecture that defined the region between 1890 and 1930, when rail access from New York and Montreal made the Thousand Islands a aristocratic retreat. Boldt, who managed the Waldorf-Astoria, designed Heart Island as a Rhineland tribute to his wife, importing Italian stonemasons and planting formal gardens. The yacht house alone cost $250,000 in 1900 dollars. Louise's death ended the project before interior plasterwork, flooring, or a working elevator could be installed. Modern restoration has added a roof to the powerhouse, rebuilt the Alster Tower gazebo, and installed interpretive panels in the tunnels beneath the island. The conservation fee supports masonry repair, window replacement, and seasonal horticulture that approximates the estate's original symmetry. Visitors disembark at the stone wharf, climb to the Great Hall, and explore unfinished ballrooms where rebar still protrudes from plaster. The contrast between opulent public rooms and raw construction zones makes the abandonment narrative tangible.