radiators

Not sure where to put this so...

Central Heating Radiators seem to always be placed beneath windows.

Why?

I find that in cold weather, I am faced with a dilema, if I close the curtains (floor length) then I lose the heat (it gets to heat the gap between the window and the curtain - not the room) or I leave them open and get a cold room through convection and ok some drafts (draughts).

Now I generally tuck the curtains up but it is unsightly or I could get short curtains but that's not an option in the main room.

So is there any reason why one cannot put the radiators to where the curtains don't interfere, i.e., a windowless wall?

Does any of this make sense? Am I just 'different'? Ok don't answer that last one....

I think the main reason for this traditional placement is because it results in the convection currents bringing warm air directly up in front of the window, creating a kind of heat barrier between the warm room and the cold glass.  That's not so much of an issue with double glazing, but it was much more important when single-pane windows were the norm.  In places where the radiator is on some other wall it can be quite noticeable that the area by the window is considerably cooler.

A subsidiary reason could be that in many rooms the wall area below the window would otherwise be unused.  Putting the radiator elsewhere would restrict placement of furniture to a greater degree.

Now I generally tuck the curtains up but it is unsightly

Excellent question, Bob. I bunch my curtains up, too. It's not very pretty, but at least the room stays warm.

Now I generally tuck the curtains up but it is unsightly or I could get short curtains but that's not an option in the main room.

I thought it was a bit silly when I saw it too. I have single pane windows and decided to double up the long curtains and make them window length. That way I keep in the heat, keep out some of the light and still be able to use my radiators to dry my clothes.

I think the main reason for this traditional placement is because it results in the convection currents bringing warm air directly up in front of the window

That's what we learned in our heat transfer class in uni. 

We lucked out in this flat and actually only have one radiator under a window.