Human sacrifices were also offered when the foundation of a new building was laid. Such sacrifices are universal, and are offered to propitiate the Earth spirits or to provide a ghostly guardian for the building. A Celtic legend attaches such a sacrifice to the founding of the monastery at Iona. S. Oran agrees to adopt S. Columba's advice "to go under the clay of this island to hallow it," and as a reward he goes straight to heaven.[816] The legend is a semi-Christian form of the memory of an old pagan custom, and it is attached to Oran probably because he was the first to be buried in the island. In another version, nothing is said of the sacrifice. The two saints are disputing about the other world, and Oran agrees to go for three days into the grave to settle the point at issue. At the end of that time the grave is opened, and the triumphant Oran announces that heaven and hell are not such as they are alleged to be. Shocked at his latitudinarian sentiments, Columba ordered earth to be piled over him, lest he cause a scandal to the faith, and Oran was accordingly buried alive.[817] In a Welsh instance, Vortigern's castle cannot be built, for the stones disappear as soon as they are laid. Wise men, probably Druids, order the sacrifice of a child born without a father, and the sprinkling of the site with his blood.[818] "Groaning hostages" were placed under a fort in Ireland, and the foundation of the palace of Emain Macha was also laid with a human victim.[819] Many similar legends are connected with buildings all over the Celtic area, and prove the popularity of the pagan custom. The sacrifice of human victims on the funeral pile will be discussed in a later chapter.