All the links seem to be broken. There's one on the official map download site but it's only ~1000x700 or something. I was looking for a larger map at least 2000+.
JUst saw this. I am sorry, but at that time 1024 in one dimension was the largest size simutrans could have handled.
On maps.simutrans.com (http://maps.simutrans.com) there are also cards 2000+.
example http://maps.simutrans.com/europe.html (http://maps.simutrans.com/europe.html)
MAP: British Isles - Download 2440x3816
MAP: South East Europe - Download 2585x2396
more on http://maps.simutrans.com/northamerica.html (http://maps.simutrans.com/northamerica.html)