We contemplated whether or not to visit the Tower of London. I had just been there last August, so it wasn't high on my list. Explained to Amt what's in there... and we decided to save our GBPs for other things.
But of course, if you've never been to London and are not likely to go there again anytime soon, it is a historical site that I encourage you to visit. So much history and the Beefeater tours are always very enlightening. The crown jewels are there too...