In one corner is Cornwall's finest, St Michael's Mount, home to a posh old family who chose the right side in the Civil War, lovely terraced gardens, a bunch of retired cannons and a collection of various other cool old weapons.
In the other corner is the pride of Brittany and/or Normandy (it's right on the border of the two French provinces), Mont St Michel. Home to security-conscious monks and sellers of overpriced baguettes, set in the middle of an enormous tidal harbour where they say the sea comes in faster than you can run and capped by a stunning fortified monastery, it's famous for good reason.
It's a tight contest. Both places have exceptionally cool architecture and great views. But despite St Michael's Mount getting bonus points for having seals, many fewer visitors and a lovely chilled atmosphere, we have to give the title to Mont St Michel. It's just bloody magnificent.
And best of all, I could release my inner toddler and go out and play in the magnificent ...
Coming up at some point in the future, our favourite UK weekend destination the Isle of Wight vs the ominous smoking lump on Bay of Plenty's horizon, White Island. Green-hilled, historic retirement home vs deadly active volcano. Place your bets.