It is not known for sure when Famen Temple was first built. Two theories exist, one is between 273 and 232 BC, the other one is during the Eastern Han Dynasty.
The temple is famous for the four Buddha's relics found in the basement, three of which are "ghost relics", used to protect the other real Buddha's relics. The "true relics" is believed to be a finger bone of Buddha, and is of great value. (But it is not allowed to take photos inside)