-First, find the map you will use. Take care that there is a little of text.
-Then, with the gimp (or photoshop) take the colour of the buildings and with the pen, erase all the text written on the buildings. This step could be long.
-(Optional step) With the "Selective Gaussian Blur" tool, homogenise the colour of the building. /!\ Buildings outline must'nt be blurry!
-"Select by colour" the buildings and copy the selection on a new image.
-Use the "Threshold " tool in order to make your building white. The background must be in the opposite colour (black). then, save the B&W image of your map.
-Open 3D software, Cinema 4D is perfect for that job, I don't know if Blender or 3DS max can do it.
-Create a "vectorizer" object and chocse your B&W map for texture. Make the Spline editable and change his type into linear type.
-Add a Loft NURBS and place the Spline in the NURBS : C4D create polygons where the buildings are.
-Make the NURBS editable, select all the polygons, extrude it, Bevel it, and you obtained a city !
-Now you can modelised complexe buldings like momuments that the present procedure make it bad.
Notes an ideas :
-Make different N&B image of your map with differents bluidings on each images in order to create quickly differents hight of buildings.
-Modelised chimney and other rooftop objetcs, then with a colners objetc in object mode place randomly objects on the buildings.
