Despite being one of the most famous islands in the world, there is a small part of Manhattan that actually makes up part of mainland America: the quaint neighborhood of Marble Hill.

Named after the dolomite marble deposits visible on the stoney crags overlooking the Hudson River, Marble Hill, while physically part of the Bronx, is technically still part of Manhattan. For the citizens of Marble Hill, it is a controversial dispute started by an engineering solution to the problem of Manhattan’s busy waterways in the late 19th century.

With dense shipping overcrowding the Harlem and Hudson Rivers, the two waterways were finally connected in 1895 by the Harlem Ship Canal. It cut through Manhattan’s northernmost neighborhood, Marble Hill, immediately turning the latter into an island, cut off from Manhattan on one side by the new canal, and from the Bronx on the other by the old Spuyten Duyvil Creek. Marble Hill kept its proud island status until 1914, when the old creek was eventually filled in, making it physically part of the Bronx, but still legally part of Manhattan.

A dispute over the neighborhood caught between two boroughs has raged ever since. In March 1939, Bronx Borough president James Lyons climbed the hilltop at 225th Street and planted a Bronx flag, claiming the neighborhood be subservient to his borough. He called it the “Bronx Sudetenland,” referencing Germany’s recent annexation of part of then-Czechoslovakia. The proud Manhattanite citizens of Marble Hill booed him down, and petitioned the city governor to make sure they remained part of Manhattan. The petition was settled in 1984 declaring the neighborhood once and for all part of Manhattan.

Today, Marble Hill itself still resembles a quaint village. Small wooden family homes, built in the Queen Anne style with porches and gardens, nestle alongside each other on the winding, steep streets that still bear the Dutch names of its original founders. The unusual curved streets follow the path of the filled in, old Spuyten Duyvil Creek, giving Marble Hill its atypical feel. As recently as 2014, the so-called “Great and Glorious Grand Army of the Bronx” planted their borough flag again in Marble Hill, demanding that the residents declare their “loyalty to the mightiest, most glorious and obviously, most handsome, borough and county of The Bronx,” only for Manhattan borough President Gale Brewer to retort that, “On the 75th anniversary of its would-be annexation by the Bronx, I am happy to declare that the flag that flies over Marble Hill is still that of the Manhattan archipelago.”

For the several thousand residents who proudly call Marble Hill home, it’s a debate that has raged since the canal was built, creating their idiosyncratic neighborhood over 100 years ago.