St. Martin's church was founded in 580 when King Ethelbert of Kent gave his Christian wife Bertha, a Frank princess, a Roman building for use as a chapel. In 597 Pope Gregory sent Augustine with 40 monks to England. They extended the building of St. Martin's church, and built the Abbey and the first Cathedral. The current Christ Church Cathedral was built from the 11th century onwards. The two Western towers were built from 1377 to 1405. The Bell Harry Tower was built in 1498. In 1170 the Archbishop Thomas Becket was murdered in the Cathedral by four knights of King Henry II. Two years later St. Thomas was canonized and the Cathedral became a place of pilgrimage during the Middle Ages.