Which ancient site is known for its massive stone circles and is believed to have served as a ceremonial site?

Stonehenge is renowned for its massive stone circles and is widely believed to have been a ceremonial site, possibly related to ancient astronomical observations and rituals. The arrangement of the stones suggests a sophisticated understanding of the sun's movements, marking significant events like solstices. Archaeological studies have revealed that the site likely played a vital role in the religious or cultural practices of the Neolithic people, making it a key focal point in prehistoric Britain.

In contrast, the other options do not fit the description of a ceremonial site marked by stone circles. The Great Wall of China served primarily as a defensive structure rather than a place of ceremony. The Pyramids of Giza were grand tombs built for Egyptian pharaohs and their design served religious purposes but does not include stone circles. The Colosseum, while a significant architectural achievement and venue for public spectacles in Ancient Rome, was not associated with ceremonial stone circles. Thus, Stonehenge stands out clearly as the site fitting the specific characteristics presented in the question.