Camelot was the castle or kingdom located in Great Britain most associated with King Arthur. It was founded by Merlin and King Arthur.  It is unclear what, if anything, of Camelot still exists. 
Real World Background
Camelot is first mentioned in the writings of Chretien de Troyes. It was originally just one of King Arthur's royal courts (Geoffrey of Monmouth portrayed Caerleon as his chief court, and many medieval romancers followed him), but as the Arthurian legend developed, Camelot eclipsed its rivals, particularly in the writings of Sir Thomas Malory. Alfred Lord Tennyson also treated Camelot prominently in his Idylls of the King, though the Lerner and Loewe musical Camelot may have particularly helped to publicize it.
Malory located Camelot at Winchester, but many people believe that the "original Camelot" was the Dark Age British hill-fort of South Cadbury in Somerset. (The location of Camelot in the Gargoyles Universe is as yet unknown.) 
- Camelot at Wikipedia, the Free Encyclopedia