Complex sentence: Osyth's burial site at Saint Mary's Church in Aylesbury became a site of great, though unauthorized pilgrimage; following a papal decree in 1500, the bones were removed from the church and buried in secret.
Split into simpler sentences: Osyth's burial site at Saint Mary's Church in Aylesbury was a site of great pilgrimage. However, following a papal decree in 1500, the bones were removed from the church and buried in secret.