Hercules brought Cerberus to Mycenae after taking him from the underworld.
Cerberus was the multi-headed watchdog of Hades, and capturing him was the final labor traditionally assigned to Hercules. Before entering the underworld, Hercules had to receive instruction in sacred rites, and some versions connect this preparation with the Eleusinian Mysteries.
Hercules was permitted to take Cerberus only if he could subdue the dog without using weapons. He succeeded through strength and endurance, then brought the creature to the world above and displayed him to Eurystheus at Mycenae. The frightened king hid in a bronze jar when he saw the hound.
The dog was not permanently removed from the underworld. Hercules eventually returned Cerberus to Hades. Mycenae is the relevant destination because Eurystheus ruled there and received the evidence that Hercules had completed the last task.