The tenth century was a dark time for those with magic. They would be persecuted by Muggles violent to magic users. So, Hogwarts was built in the Scottish Highlands, and hidden with several spells to make it impossible for Muggles to enter. Unlike us magic users, who can see a massive school, Muggles can only see danger signs warding them off. 

     Hogwarts has a very large history with ancient magic. Albus Dumbledore said that he doesn't even know all of the school's secrets. A good amount of it's design remains a mystery. Some say that Rowena Ravenclaw came up with the name Hogwarts when she was dreaming of a warty hog that led her to the edge of a cliff (which is where the school is located!!). It is not known whether this is actually true.