As the country with the oldest railroad network besides England and one of the most dense railroads in the world. i think Belgium definitely deserves a Train Sim World route. There are a lot of suitable roads that Belgium has to offer. If i could choose i would suggest the Antwerp to Brussels route. The route with it's 40km in length is a very bussy commuting route with hundreds of trains per day. It also includes Brussels-Mechelen which is the first train route in the world outside of England. The most notable landmark would be Antwerp central station which is arguably the prettiest train station in the world. The railroad operator in belgium (NBMS) has a variety of rolling stock including double decker which are very common on this route. On this route there are also internation services including the Eurostar, Thalys and NS (netherlands) local trains.