nice one. Paris Hilton was perfectly fair. Wish I'd thought of it.

I think the rule would usually be they can all be preceded by the same word, otherwise it's a bit unlikely you'd spot it

Very nice, this hit the sweet spot for me, creative and challenging enough to be interesting but very fair and not ridiculously obscure. I liked the idea for the "Treaty" group a lot but I thought that was the weakest member in the group; I think you could have replaced it with a stronger candidate. "Wall" might have been a nice one? Or perhaps "Mule"?

Thank you Wolfdog! .. Funnily enough, I did have both 'Wall' and 'Mule' in that set originally, but I thought that 'Mule' might be a little bit too obscure and didn't want to have 2 landmarks in the group so kept 'Bridge'.

Totally agree that some of the grids can be overly obscure, which saps the fun out of it for me.