By this point, the most beloved train station in America didn't look so good. That photo above is not colorized: The marble had been stained by over half a century of pollution. And with the decline in train travel compared to the rise of driving and flying, a train station this grand was no longer necessary. The successor station would be utilitarian at best -- and a commuter's nightmare at worse.
When the Pennsylvania Plaza complex opened in 1968, including the new Madison Square Garden above it, Penn Station had become completely subterranean, and it went from being one of the most beloved transit centers in America to one of the most hated.
But the original station's destruction spurred the landmark preservation movement in New York City, which helped to save Grand Central Terminal in the 1970s, Carnegie Hall in the 1980s, and so many other great buildings. Still, not every great building was saved: Once Lincoln Center opened, the original Metropolitan Opera House was demolished in 1967, and a boxy skyscraper was put up in its place.