South Ferry station in New York City is ancient; one of the original terminals of its line. It was built back when the best practices for subway construction weren't still fully established, and so ended up a bit weird: The whole station is a very tight reversing loop. The advantage of that structure is having essentially zero downtime when changing directions. The disadvantages are a giant gap between train and platform (bridged by movable platform extensions, visible in the center), a rather short platform altogether that can't easily be extended, so only the first few cars can be loaded and unloaded; and the tight curve reduces speed when entering and leaving the station, is noisy and requires intense maintenance. Of course, it also wasn't wheelchair accessible or anything. And since it serves the Staten Island ferry, it does see quite a few people, which makes all these problems even more visible.
So they replaced it with a new, top-modern terminal station in 2009. Accessible, beautiful, operationally simple, high capacity, everything was perfect.
Then Hurricane Sandy came and basically destroyed the new station. So since then, the old loop station is back in business, as a living piece of New York transit history. Current plans are to switch back to the new station in August 2016, so if you want to see it, you should hurry.