(Just in case any updates are forthcoming). Heavy artillery is stuck in the city were it is built, i.e. it cannot travel over terrain or on roads. However if a transport enters the city then it can take HA with it when it leaves, this could be useful for shipping HA where it is needed. 

However the transport has no means of unloading HA, the unload command adjacent to a city has no effect and if the transport enters the city and unloads the HA are still onboard when it leaves. The only working method seems to be to ship to another city and then scrap the transport.

Also playing the important cities variant it can be very difficult to see neutral important cities as the star is not at all prominent against a B&W background.

Heavy Artillery cannot travel by default.  it is not a mistake in the game.  If you want to move on the same landmass, that is what trucks are for.

If you are having unload issues, this might be an error in your install.  I load and unload all the time for Heavy Artillery in games I am playing using both trucks and transports (even a Transport Aircraft from time to time).  Unloading of Heavy Artillery is always in the same space as the transporting unit, so you cannot unload everywhere.

Plus, make sure you have unit stacking enabled for the game you are playing.  Without unit stacking I am not sure you can ever unload outside of a city or fortress.

Cheers :)

Thanks, I have stacking turned on This is a Mac if that matters.

I wonder if it has to do with auto load/unload? I have that turned on.

If you wish to place an HA in an open space, use "drop" on the truck