Next to the Forest of Stone Steles Museum is a hidden temple built between 168 and 189, making it at least 1827-years-old. Coming from a place with a 500-year-old history, this just blows my mind. Although the buildings themselves aren't that old, the place has been used as a temple for that long. Still amazing.
The Wolong Temple is another one of those places that are a hole in the wall. You have a busy avenue right beside and modern shops and buildings surrounding it. The front door is temple-like, but if you didn't know what was inside, you'd just walk past it. I almost didn't go inside.