Mephisto 2658

[erundle]

It seems the answer to 12a is DOME. Can someone please explain the ".... going back over 400 years" bit please. This was my last clue. I spent more time trying to figure the bit in quotes than I did on the rest of the puzzle.
Thanks in advance.

[mahonia]

What is the full clue?

[GetOverIt]

The full clue is

12 Old cathedral ruin going back over 400 years (4)

[bibblebub]

possibly:-

ruin = DO
going back over 400 years = M.E. [middle english]

maybe it's an old clue because it's now over 500 years

[GetOverIt]

Looking back on the crossword... your OME are correct , I think I went with dome because Kayakamina suggested it!

[erundle]

Thanks to you all - I see it but, by God sir, I don't like it. As the actress said to the bishop.