Elephant Mountain, also known as XiangShan (象山). Is located in the South East of Taipei city, not far from the 101 building. It's very easy to get there by MRT, only 15 minutes from xiangshan station.
We did a small trek of an hour, but it is possible to walk a bit further.
I had been there before a few times, but I didn't remember it being that crowded before.
I don't have much things to say about it. Xiangshan is a nice place to go for a walk on a lazy day in Taipei. Probably better to go the evening to avoid the people.