The Parque Arqueológico do Solstício (Solstice Archaeological Park), referred to in academic sources as AP-CA-18, is an archaeological park located in Amapá state, Brazil, near the city of Calçoene. It contains a megalithic stone circle, colloquially known as the Amazon Stonehenge, consisting of 127 blocks of granite, each up to 4 meters tall, standing upright in a circle measuring over 30 meters in diameter at the bank of the Rego Grande river on a hilltop. Archaeologists believe that this site was built by indigenous peoples for astronomical, ceremonial, or burial purposes, and likely a combination. The function of this megalithic site is unknown, much like other sites such as Stonehenge, a much older site in Great Britain.