The third building that is part of the unesco listing in Canterbury - and from the front door you get a wonderful glimpse of the Cathedral - although St Augustine's Abbey is completely hidden by the yew trees.
This is the oldest parish church in England that has been in continuous use. There was a roman christian chapel on this site and its walls form part of the chancel. In the 6th century King Ethelbert of Kent (a pagan) had the church built for his christian bride, Queen Bertha
<a href="http://whc.unesco.org/en/list/496" rel="nofollow">whc.unesco.org/en/list/496</a>
