The citadel dates to the Galatians, was occupied by Alexander, the Romans, even the Mongols.
One of the most memorable meals I ever had was at a restaurant (converted section) in this castle. Was with a bunch of very senior Turkish politicos. Wonderful warm evening, really good traditional Turkish special occasion dish (braised lamb over eggplant puree), great view of Ankara spread out below us. Lots of raki and Cuban cigars.
Just for grins, this is the spice market right at the foot of the castle: