Why is that?

I don't like basements. It started, I think, when I was a kid and one of my siblings would switch off the light and slam the door at the top of the basement steps, leaving one or two of us down there in total, creepy darkness.
What is it about basements that scare us? Is it the darkness? Is it the dankness? The small or non-existent windows? Does it remind us of the grave?
Why is it, in horror movies, the stupid, clueless girl hears a noise and goes down to investigate?Why is the noise in the basement?
Why is there always a basement?
I'm sitting on the couch watching another horror movie. Here's how it plays: stupid, clueless blond girl is alone in the house. She hears a strange noise and - instead of locking herself in the bedroom, hiding under the bed with her cellphone and calling 911 - goes down the stairs. Surprise, the noise seems to be coming from the basement. She opens the basement door and says," Hello? Is anybody down there?"
YES! You idiot! The monster is down there! Haven't you ever watched a horror flick?!
She takes her first tentative step onto the rickety wood basement stair and reaches up to pull the tiny, little string attached to the one lightbulb in the whole screamingly, creepy basement.
A couple more steps and. . .

Now, in a crime movie the victims get murdered in any convenient room in the house. A stabbing in the kitchen, a gunshot in the study, a bludgeoning in the bedroom.
I can stand that.
But the basement?

I'm screaming at the tv set, jumping up and down in a panic, dreading the start of the slasher music that inevitably accompanies the girl's murder.
Stupid, clueless girl. Just stay upstairs and you'll live.
But she never listens. Next movie will see the reincarnation of the stupid, clueless girl. Maybe she'll be a brunette this time.
But, always the basement.