@Besu: For the first map you posted, you should perhaps use shift-mapping to make some of those holes extend right up against the wall. I think that would make them look a little better. You've also got some shift-mapping errors with the darker ground tile being completely flat against the hole tile; because the hole tile has a light outline, you don't want to shift-map the darker ground tile up against it because it doesn't look good.
For the second map, you have a piece of railway track that is doing absolutely nothing. What is that there for? What is its purpose? If this is a mine then the track would go outside the mine since the miners would be using it to take coal/ore out of the mine ready for transportation. The track would also extend all the way through the main section of the mine (and also down any major break-out tunnels, but not down minor tunnels) so that coal/ore from deeper in the mine can be easily transported back to the entrance.
Finally, as with some of your other maps set in natural environments, you have too many areas that are a long sequence of straight tiles. That doesn't look right for a natural environment like a forest or a cave. People have mentioned this for the other maps that you've posted also.