U Thant Island, officially called Belmont Island, did not exist until the 1890s when it was formed as a byproduct of infrastructure excavation. In the 1890s, piano manufacturer William Steinway initiated the construction of trolley tunnels beneath the East River to connect Manhattan and Astoria, Queens. The granite rubble and landfill from digging a shaft down through the outcropping known as Man-o’-War Reef accumulated until it created a small, half-acre island above water. Steinway died in 1896 before completing the tunnels, which were finished by financier August Belmont Jr. in 1907. The island’s legal name, Belmont Island, honors the project’s eventual financier. The tunnels—Steinway Tunnels—are still in use today by the 7 subway line, running directly beneath the island.
