I used "SketchUp Make 2017" and the extension called "Bitmap to Mesh".

I got the greyscale gradient from tangrams heightmapper.

0.026952632591590312.png0.026952969294809087 - no lines.png

And I did the aligning phase using the lines of the streets from tangram's site and a "first stage" taken from Iberpix to get where the medieval fort was placed:

iberpixHeigtmap.PNG

When setting the X to Z scale, I used the number that tangram's site provides.