There is another way to do this:
A few months ago when I was doing City Terrains (see my sig for Manhattan Terrain), there were some circumstances when I wanted to put specific buildings in specific spots, for instance, on the Gotham City map for King Arthur's Super Scenario, I needed to place an amusement park, the prison and power plant, and a scientific research park:
My method for doing this is painstaking, but rewarding. First, I pick a terrain type that I won't need elsewhere, like Marshes. In the above example, the prison and power plant are Tundra Trees (Tundra files were modified to look like grassland), the Research Park is Jungle Hills (the jungle is the tall trees surrounding it), and the Amusement Park is made mostly of resource icons.
So having chosen a terrain type to modify, I take a generic version of that terrain and make a "blank" template, then number each diamond on it.
Then, in the editor, I put that terrain onto the spot where I want my new building, and note which numbered tiles make up the four squares (for instance) of my building.
Then I go back to my graphics program (GIMP) and remake the terrain file so that the four pieces of the building occupy those squares. When I reload the biq,
Voilà! a prison, stadium or castle has appeared in that spot. Now, because the terrain files often have many more than four tiles to work with, I'll usually try to use all of them somewhere in a city terrain, so that the Marsh file, for instance, will have the various pieces of many buildings on it. One caveat: these tiles often repeat in various configurations, and the only variables seem to be the surrounding terrain, so in order to make some buildings I'd sometimes have to place, say, an open grassy spot next to it.
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