Kūkaniloko Birth Site, also known as the Kūkaniloko Birthstones State Monument, is one of the most important ancient cultural sites on the island of Oʻahu. In 1973 it was first listed on the National Register of Historic Places and its boundaries were increased in 1995, after 5 acres (2.0 ha) of land which included the site became a state park in 1992. The site was the location for some of Hawaii's royal births. The Kukaniloko birth site may have served as astronomical function.