The IRT Lexington Avenue Line is a major subway line in New York City, part of the New York City Subway system. It runs from East 180th Street in the Bronx to Brooklyn Bridge–City Hall in Manhattan, primarily serving the Upper East Side and connecting various neighborhoods along its route. Opened in 1904, the Lexington Avenue Line is known for its high ridership, making it one of the busiest subway lines in the city. It features several key stations, including Grand Central–42nd Street and Union Square, providing access to important transit connections and local attractions.