I found this website that has a collection of old paintings, sketches, maps, etc.
For example in the search area enter anything you want to look up and you may get sketchs, paintings, maps that were drawn during colonial era.
http://jcb.lunaimaging.com/luna/servlet/view/search?fullTextSearch=full…
And check this on on the presidos and map of Texas year 1769. You can zoom it up real close with clarity:
http://jcb.lunaimaging.com/luna/servlet/s/013g9o
http://jcb.lunaimaging.com/luna/servlet/view/search?fullTextSearch=full…