As I know, ANY= 1-7 lvl of ruin...But when I tried to attack a ruin below my level, it says " You can't attack such a low lvl ruin".
So, in this case, why the quest is called "ANY ruin" ????

Just a waste of time searching for a lower ruins to complete the quest asap, and when u try to attack them, it's not possible...
Cheers !
BDG