Well, I think the real problem is with the round towers. I haven't drawn them correctly for an isometric view, but there's also a slight inclination of the vertical lines that makes them bend over the village as you say. I still have to correct this. Thanks for pointing it!

Regarding the wall that blends with the roadway, I still have to erase a dirt road under the two close towers and finish the main gate, wich at the moment is just sketched.

As for the vegetation, it's a town in a desertic area, but you are correct, I still have to add some farmlands here and there though I haven't decided yet wich way to go as far as implementing it on the drawing. I've tried some textures I have, but they're top down views so I have to draw or add a perspective... I'm yet undecided.

Thanks for your comments.