Keep your lovin' brother happy!
Imagine roman and greek player loose Syracusse or Rome after having played the Servian Wall and Heights of Epipolae. Could the player controlling now these spaces benefit from the +2 to siege roll, or are the benefits lost?
The controlling player receive the benefits as well.
PS: does the the greek elephant marker count as a CU, or just is a bonus of + 2 attack?
It is not a CU. It's just a bonus.