It is a nearly universal tendency amongst human cultures to consider certain places holy. Christians, Jews, and Muslims are well-known for declaring particular places sacred, and there have been wars fought over guardianship (witness the Crusades -- and note that Palestine was always referred to by Crusaders as "the Holy Land," a designation sometimes still used). Even today, skirmishes erupt over who has control, or even access, to certain sacred sites. For several years, there has been an ongoing feud over which sect of Christians -- Ethiopian or Coptic -- has the ownership of the Deir-al-Sultan Monastery in Jerusalem, a site which is next to the Church of the Holy Sepulcher and has connections to the life and death of Jesus. This particular incident might be funny if it weren't a microcosm of a tendency which has cost millions of lives, and if the monks in question weren't so deadly serious themselves.
However, such perceptions are not by any means limited to Judaism, Christianity, and Islam. Even the Buddhists, whose philosophy emphasizes "non-attachment" to the physical world as the cardinal virtue, have holy sites. These are mostly connected with the life or death of Siddhartha Buddha and are the objects of pilgrimages from Buddhists around the world. The Australian Aborigines have Ayers Rock (Uluru in the language of the Natives), which is central to their creation stories. The Devil's Tower in Wyoming is sacred to the Sioux (and apparently also was of some significance to the aliens in Close Encounters of the Third Kind).
I find this tendency fascinating. Sacred sites seem usually to fall into one of two categories -- they are either places of historical significance (a friend of mine is working on a novel that has as its central theme the contention that the Vietnam War Memorial is a holy place), or places that have some natural oddness that makes them stand out, that begs an explanation. These latter ones I find the most interesting. There is a universal need in the human brain to explain our environment, and apparently if no natural explanation makes itself known, then we almost always respond by simply making one up and telling it convincingly enough that it is remembered.
I can't say that I'm immune to this. I self-identify as a rationalist, but a friend of mine claims (with probable justification) that I doth protest too much. She once stated that if I had the balls for it, I'd be a mystic, and that in a previous age I'd have been a monk. That rather curious claim notwithstanding, I have to admit that I have been in places which strongly affected me, which (had I the balls to be a mystic) I might consider sacred. One of them is Ahlstrom's Prairie, a highly peculiar place in Washington State that I used to pass through while hiking to the ocean on the Olympic Peninsula. There's a boardwalk trail on the hike to the mouth of the Ozette River, and most of the way you are in dense Douglas fir forest, dripping and silent, with nothing but the clunk of your hiking boots on the wood planks to break the quiet. Then, without warning, you are in an open meadow, a strip of land with not a tree, perhaps a quarter of a mile across and maybe two miles wide (although I never explored it well enough to know for sure). It is an odd enough spot that I wouldn't be surprised if the Quiliute and Makah Natives who lived in the area considered it sacred. For my part, I thought it was a little creepy, and was always glad to cross it and get back under the cover of the dark trees.
Another spot in Washington, not nearly so remote, is the Mima Mounds. Near Littlerock, Washington, and right off of Interstate 5, is a wide prairie dotted with relatively circular grass-covered mounds, the largest of them about thirty feet across and maybe eight feet high. Originally thought to be Native burial sites, they are now thought to be the result of some unknown geologic process, possibly glacial. All I know is that they're spooky and mysterious. I can easily see why someone might consider this a holy place.
Lastly, I would be remiss in not mentioning a place I visited on a hiking trip in the north of England. I have always been interested in medieval history, and I made a point of visiting a number of abbey ruins, monasteries which were abandoned when Henry VIII decided that Catholicism wasn't his cup of tea, but Anne Boleyn was. Most of them were of solely intellectual interest, but one of them -- Rievaulx Abbey -- strikes me as one of those places which did not become sacred because it was the site of a monastery, but became the site of a monastery because it was sacred. It sits in a little, cup-shaped valley, with a narrow river running through it, and as I sat on a rock under the branches of an oak tree, dangling my bare feet in the cold stream water, I could almost become convinced that there was something to the idea of a place being holy.
Almost. And so I don't have my Skeptic's License revoked, allow me to state for the record that I realize that in all of the above cases, it was just the oddity, remoteness, and beauty of the site acting on my emotions and my imagination. I don't really believe that there's anything peculiar about any of these places, above and beyond the purely natural and aesthetic.
Be that as it may, there is a part of me that wishes it were true. It's not scientific, it's not rational - but it would be awfully cool.