Excellent question.  The bastards destroyed my gold mine but I was unable to retaliate in kind.  So instead I took over their city.

Seriously, I'd like to know.

Yes.  My gold mine was well within my territory and it was destroyed.

I took my sovereign with a bunch of units to destroy their gold mines.  When I was on top of the gold mine, there no option.  I checked all of the sovereign's actions and didn't see anything that would allow me to destroy it.

Yup to destroy enemy improvements I believe three conditions must be met:

1. having researched Fortification (I always do this now so not 100% its required for improvements but given you could not I think it is required because I can)

2. be at war with the opponent.

3. move onto the improvement so long as it is not part of the city.

If the cases it is part of the city, Razing the town/city/settlement will destroy the improvement.  I saw this tonight in my 1.07 game.

Cheers,

Gene 

Pillager #1 (with bandages covering his arms and face)" Yeah, we really messed up at that last place.  We started burning the city and then starting looting.   Just didn't worki as well"

Pillager #2 "Good thing we found that book in the lost library 'How to Pillage the civilized way', now we know how to do it."

Yea, you have to research magic in order to breath.