Cadfael and Robin Hood

I'm confused. I thought Cadfael helped hunt out murderers in Shrewsbury during the first half of the 12th century, while Robin Hood robbed from the rich to give to the poor around Nottingham in the second half of the 12th century.

If ITV and the BBC are to be believed, however, it would seem that Shrewsbury Abbey and Nottingham Castle are actual the same building!

In reality of course it just happens that both TV series were filmed on location in Hungary. Apparently it is one of the few places where you can pretend it is still 12th century England.