Scariest Places on Earth

I just finished watching an episode of the very campy show "Scariest Places on Earth". The show got me thinking. I've been in a decent number of abandoned places now. I'll admit that I've not been at these places at night. The one place I am reluctant to enter is a location I would not enter in the daytime.

I'm wondering this... what is the scariest place you've been to? Was the feeling from the surroundings or a psychic vibe? Was the feeling influenced by the time of day? Thanks for sharing!