I didn't spend long in Santiago, it was a stepping stone between Easter Island and the Atacama desert, but I did have a (so far) unique experience there. I was awoken at 6am by the bed being shaken. At first I didn't know what was going on, or even where I was. Then as I surfaced from my sleep I worked out that it was an earthquake! It only lasted about 5 seconds, so I rolled over and went back to sleep. Well, what else could I have done?
I also had a good stroll around the centre early on a Sunday morning when (it seemed) every one else was still in bed. The centre has some fine colonial buildings that house the different elements of the Government.