As long as the game give you the option to build 2 stone wall gates inside the Great Wall Gatehouse, I tested what happen when you do this. If one of the gates is destroyed, the Great Wall Gatehouse automatically gets destroyed too and you can’t rebuild again the landmark because it dissappear forever on that match.
How to make this bug:
- Buid the Great Wall Gatehouse on a wall.
- When it’s done, build two stone wall gates inside the Great Wall Gatehouse.
- Destroy just one stone wall gate and see what happens.
- You are not able to rebuild the landmark because you can’t select the boundaries.