The Cobble Hill Tunnel (also known as the Atlantic Avenue Tunnel) is an abandoned Long Island Rail Road (LIRR) tunnel beneath Atlantic Avenue in Brooklyn, New York City, running through the neighborhoods of Downtown Brooklyn and Cobble Hill. When open, it ran for about between Columbia Street and Boerum Place. It is the oldest railway tunnel beneath a city street in North America that was fully devoted to rail. It is also deemed the oldest subway tunnel in the world by the Guinness Book of World Records. Construction and operation Originally built as an open cut, construction began in May 1844, and opened for use on December 3, 1844, but was not completely finished until mid-1845. It was built mainly to satisfy public demand for creation of a grade-separated right of way for the Brooklyn and Jamaica Railroad (later Long Island Rail Road) on its way to the South Ferry at the foot of Atlantic Street (later Atlantic Avenue), where passengers could catch ferries to Manhattan. The construction of the cut also lowered the LIRR's grade through Cobble Hill. Around five years after opening the cut was roofed over, converting it into a tunnel. As originally built, the cut was wide and long. Once roofed over, the interior height of the newly created tunnel was . In exchange for building the cut, the City of Brooklyn granted the B&J permission to operate its steam locomotives on Atlantic Street west of Fifth Avenue (then Parmentier's Garden/Gowanus Lane), all the way to Brooklyn's South Ferry (the present location of Brooklyn's Pier 7). Prior to the cut being built, the LIRR's western terminus was Atlantic Street at Clinton Street. Train cars were hauled by teams of horses along Atlantic Street from Clinton Street to Parmentier's Garden, where steam locomotives were attached. While the cut was being built, the railroad operated to a temporary terminal at Pacific Street and Henry Street. The Cobble Hill Tunnel was part of the first rail link between New York City and Boston, Massachusetts. The railroad connected Lower Manhattan via the South Ferry to Greenport on the North Fork of Long Island, where a ferry connected to Stonington, Connecticut, where a rail link continued to Boston. This avoided some difficult construction of bridges over the rivers of southern Connecticut. In 1848, the New York and New Haven Railroad Line was completed through Connecticut, providing a direct, faster rail connection