In the religion of the ancient Celts who lived in Iron Age Europe from 700 BCE to 400 CE, certain natural sites like springs, river sources, and groves were held as sacred. These places, as well as some urban sites, often had purpose-built temples, shrines, and sanctuaries. Here, druids performed rituals and prayers while votive offerings of precious goods, as well as animal and human sacrifices, were given to the Celtic gods to gain their favour and ensure the continued success of the community. Celtic religious practices and sacred sites initially survived the expansion of the Roman Empire, but from the 1st century CE, they came under direct attack and prohibition. Following the spread of Christianity in Late Antiquity, the Celtic religion all but disappeared from mainland Europe.
This is a companion discussion topic for the original content at https://www.worldhistory.org/article/1710/sacred-sites--rituals-in-the-ancient-celtic-religi/.