Rivers don't do anything?

[Harald]

After playing the demo a couple of times I realised that rivers don't seem to connect cities for trade routes. There doesn't seem to be any tech unlocking this either. I'm prabably missing something but I can't really see a reason build right next to rivers.
So is there any reason to build next to a river or is it better to build further away so you can use the extra hex for fertile farmland*? What am I missing?

EDIT: I probably should add that I know that there is an increase in commerce on hexes next to rivers as well as they act as natural boundaries for units.

*When it is unlocked.

 

[stealth_nsk]

Some buildings could only be built if city is near a river.

 

[Resender]

Yeah I'm seeing this to in demo as egypt where you satrt near a long river cities besides the same river don't connect which is odd.
The roads are splines Ok, but they look poor at intersections