Camelot is a location in England that is legendary for being the center of the kingdom of King Arthur and his Knights of the Round Table, existing in peaceful harmony as long as the king holds the magic sword Excalibur. It appears in the Season 9 episode "The Smurfs Of The Round Table".
In the story, King Arthur's nemesis Morgan le Fey stole Excalibur and used it to turn the king and everything in Camelot into wax, turned Merlin into a rock, shrunk Sir Lancelot down to Smurf size, and cast a spell on the sun to burn hotter so that everything in Camelot will melt away. The time-lost Smurfs who showed up on the day that it happened took it upon themselves to get Excalibur back from the evil sorceress with the help of Merlin and his magic wand Sir Will. Upon their successful return, with everything restored to normal, the king honored his guests for their bravery by naming them "the Smurfs of the Round Table".