The much-talked-about 7 line subway extension on Manhattan’s West Side isn’t the only mega-infrastructure project making progress in New York. Construction continues far below the streets of Manhattan’s East Side as crews tunnel through bedrock for the Second Avenue Subway line. This week, the MTA released a gallery of photos showing construction progress on stations between 63rd and 73rd streets. The photos show the enormous rock caverns that will one day be subway stations being prepped with liners, rebar, and concrete casing. According to Gothamist, construction progress varies by station, with the 72nd Street station 96 percent complete and the 86th Street station 42 percent done.