Just a small nitpick though, the base maps that were used are not correct, they are post 17th century.
you can find a few correct maps on this wiki page:
http://nl.wikipedia.org/wiki/Romeinen_in_Nederland
And in this book in google books:
http://books.google.nl/books?id=K7RtK8T11sAC&printsec=frontcover&source=gbs_v2_summary_r&cad=0#v=onepage&q&f=false
you can find a few correct maps on this wiki page:
http://nl.wikipedia.org/wiki/Romeinen_in_Nederland
And in this book in google books:
http://books.google.nl/books?id=K7RtK8T11sAC&printsec=frontcover&source=gbs_v2_summary_r&cad=0#v=onepage&q&f=false