I've played Simutrans for a while now, gotten a lot of experience (such a wonderful game!) but I was wondering: What is the purpose of the headquarters?
Headquarters have not any special purpose - but it shows financial statistics too (like icon of financial statistics in menu bar).
But as you may see, its build cost and also maintenance is very high - and so it is usable only if you have very big company with very big earning of money. Else it will send you to bankrupt.
And a headquarter will attract passengers and mail.
... oh, I forgot on it ... great many passengers and post. So it is good to build it somewhere where it will be easily accessible. It means close to main transportation hub of any city.
Ah, I see. Thank you very much.