The Temple of Sirius is a temple (and launch site) built by ancient alien astronauts.
The temple itself was carved by the ancient astronauts, because space helmets are carved into it and space suits were placed all over, like suits of armor.
The New Scooby-Doo Mysteries
The celestial orb opened the secret passage to the treasure room which was home to a huge golden egg embedded with millions of diamond, rubys, emeralds and sapphires (as Velma Dinkley said she would have hated to meet the chicken who laid it). It turned out the egg was actually a spaceship that the ancient astronauts crash-landed in millions of years ago.