There were giants in the earth in those days, or so they say…
Genesis is pretty unequivocal on the subject of the existence of giants. But then again, Genesis says a lot of wacky stuff. It's not a textbook, is my point: it's a religious text. (Also, there is a lot of argument over the word "giants," which many Biblical scholars feel is just a mistranslation of a Hebrew word that means "apostate.")
Regardless, there are a lot of claims coming out of Romania these days that giant skeletons have been found in the Romanian countryside. These stories are made far more confusing because most of them have been illustrated with pictures that were taking from a Worth 1000 Photoshop contest to Photoshop in some giants.
According to Romanian lore, there were giants living in the far inaccessible mountains, as proven by giant thrones carved into the mountain sides. The remains of the giants have turned up from time to time, but the CIA keeps suppressing the information. (Why?)
Incidentally, put away your thoughts of a giant the size of a five-story building. According to reports, the giant skulls were only 2-3 times larger than that of a modern human.
Most cultures have giants in their mythological catalog of lore. It doesn't take much to imagine a monster that's "a person, only bigger." These may also be stories that linger from the ages-old oral traditions, from a time when humans coexisted alongside Neanderthals, back in the Ice Age.