The historic ruins of Monasterboice are of an early Christian settlement in County Louth in the Republic of Ireland, north of Drogheda. It was founded in the late 5th century by St. Buite who died around AD 521 and was an important centre of religion and learning until founding of nearby Mellifont Abbey in 1142.The site houses two churches built in the 14th century or later and an earlier round tower, but it is most famous for its 10th century high crosses.The round tower is about 35-metres tall, and is in very good condition, although it is not possible to go inside. It is believed that it was built as a refuge for the monks against the Vikings, although this theory has been widely disputed. The passage of time has laid down layers of earth so now the doorway is almost at ground level. The monastery was burned in 1079.