Well the idea of this map came from the geographical position of my hometown, it a pretty big island in the middle of a river. The iland mains aspect is the "Mont Royal" on its center. Its not 100% accurate, but whit the iland and the low-land around its a pretty accurate view of montreal(also the real island is alot bigger).
You can make a really cool stronghold, I recomend using the moutain for your keep. Whit only 1 entrance to the moutain you will need to carefully plan the layout of farms and all to keep your population triving.