@dvlenk6 - thanks - here are exactly the kind of images i need for the streets!

@fran - mills are  thatched, roofing felt is never used - for textures of thatched surfaces see the site dvlenk6 mentioned - i saw a lot of good ones there. it is best to take a dark texture and it has to go from the top to the bottom.
don't worry about the back of mills - they are exactly the same as the front.
if there is something you need to know about mills, ask me, almost everything can be found if you search dutch sites, which will be difficult for you, of course.

• could you give me the dimensions of the mill so that i can make a kind of hill to put it on? there has to be quite some free space around it because of the sails.

"The light at the end of the tunnel may be an oncoming train"