The first thing I missed out on: the Japanese Government General Building of Korea.
After Japan annexed Korea, they built this huge modern government building on the grounds of one of the main palaces of Seoul, as a huge geomantic fuck you to the Korean people.
Here you can see it towering over the traditional gate to Korea's main palace.
From the other side, you can see how the palace is intentionally overshadowed by the building.
The building more or less survived the war and came into use by South Korean governments for decades.
In 1995, demolition slowly began. In 1996, I visited Seoul for the first time and saw the building all covered up in a green netting. I would confused why they would demolish a perfectly ordinary building, not really understanding the history behind it.
Now, looking back and knowing what I know about Korean demolition, I could've easily slipped past the net and explored this significant building right before it was destroyed.
Here's a demolition picture taken sometime after my visit.
The palace has been undergoing a long-term reconstruction project to restore it to pre-Japanese occupation and is now one of the country's top historic tourist sites.