how did charley reach the third level of the grand central station

Charley reached the third level of the Grand Central Station by accident. One evening, while hurrying home and looking for a train, he went down to the second level and then discovered a hidden doorway and tunnel going further down. Curious, he followed the tunnel and took the steps downward. The corridor turned sharply left and slanted down, leading him to take a short flight of stairs. Eventually, he came out onto the third level of the station, a level that officially doesn't exist at Grand Central, which has only two levels. This third level was unlike the modern station: it had fewer ticket windows, old wooden booths, gaslights flickering with open flames, and brass spittoons. Charley found himself in what seemed like a scene from the late 19th century, with people dressed in period clothing, old-fashioned trains, and architecture reminiscent of the 1800s. This mysterious level felt like a gateway to an older, quieter, and simpler world from 1894, contrasting with the busy modern times above.