I really like the neoclassical architecture. There isn't that much in Seoul, but what they have left is well maintained. They famously tore down one building, but it really annoied them.
They are currently working on a 450km/h max train, it will probably cruise around 420km/h. A few of the rails are straigh enough to support it and all concrete ties, too. Any faster than that and it will have to be maglev.
Oddly, when riding it, it doesn't feel that fast because the windows don't open and it's so smooth.