Hogwarts was founded by four of the greatest wizards of all time, there were two witches among the four and two wizards. Salazar Slytherin, Godric Gryffindor, Rowena Ravenclaw, and Helga Hufflepuff. The four gathered together with a common interest of creating the best school of all time. The school was founded sometime during the tenth century, though the exact date is not known. The founders put many protections on the school because at the time Muggles (Non wizard kind) suspected the making of wizards and witches, and wanted to put an end to it. One of the many protections was to make the castle look old and deserted to muggles, with a sign of danger if they got near. The castle was placed in Scotland away from muggle eyes. It was also made impossible for any witch or wizard to apparate into school grounds. Once the castle was built and protected, the founders each made their own house to take in the students they wanted. Gryffindor wanted the most brave, Ravenclaw the most intelligent, Slytherin the most sly and cunning, but most importantly only purebloods, and Hufflepuff who wanted the most kind and accepted the other students that weren't wanted by the others. Some time during history Salazar Slytherin wanted only purebloods to be accepted into the school but the others disagreed, Slytherin had enough and decided to depart from the group. He left the chamber of secrets and only his heir would be able to open it again.