Mobupinchu

Mobupinchu is an ancient lost city that appears in the Sonic Underground episode "Artifact". It is the most sacred place in Mobian legend and is home to many rare and priceless treasures. The existence of Mobupinchu was thought to be a myth until Doctor Robotnik chanced upon the valley outside the city. Robotnik continued to excavate in search of the real Mobupinchu, only to be stopped by the Underground, who then found the city themselves. The treasure of Mobupinchu belongs to all the people of Mobius, and it is the Underground's duty to keep it safe.

History
During a party for the aristocrats of Robotropolis, Doctor Robotnik announced that he had recovered some valuable artifacts from Mobupinchu and attempted to auction them off so he could raise money to build more SWATbots. Sonic, Sonia and Manic, who were posing as waiters, disturbed the auction and stole the artifacts in the chaos. Robotnik eventually returned to the valley of Mobupinchu to oversee a digging operation to find the true city, sending Sleet andDingo to recover the artifacts that the hedgehogs stole.

In order to stop Robotnik from digging up and selling Mobupinchu's treasure, the hedgehogs had to find the city. Sonic and Sonia had one of the artifacts analyzed using the Gamma Spectrum Analyzer at Mobius University, and theProfessor told them that it was not from Mobupinchu. It was actually a 500-year-old weapon used in the last Mobian war before Robotnik began his reign; his archaeologists had lied to him. Manic had sold the other artifact, an orb, to a salesman called Vince, who then sold it to Bartleby, and the hedgehogs had to retrieve it before anyone was injured in the orb's explosion.

Sleet and Dingo, having been informed of the orb's whereabouts by Vince, kidnapped Bartleby and the orb, taking him to the excavation site at Mobupinchu where Robotnik was waiting. The hedgehogs pursued them all the way, and after an uncomfortable climb up a mountain (courtesy of Sonic), Manic realized that they were in the valley of Mobupinchu. Robotnik was about to reprimand Bartleby when Sonic barged in and grabbed the orb, which eventually exploded and destroyed Robotnik's digging operation.

Afterwards, the hedgehogs found their way into an underground cave and discovered the real Mobupinchu. They found a treasury full of gold and gemstones, and Manic was about to hoard a jewel when Sonic pointed out a message from Queen Aleena Hedgehog|their mother]] on the floor saying that she was guarding the treasure. At the end of the episode, it is revealed that Queen Aleena had witnessed their defeat of Robotnik and was watching them from a distance.

Trivia

 * The name "Mobupinchu" is a reference to the real life site, Machu Picchu.