The castle is well worth a visit at the very least for the view of Ankara and to meet some more…read morecats. Originally dating back to Roman times, 476 and 33 BCE, Roman elements were reused by Seljuk, Byzantine, and Ottoman builders, it's a formidable mishmash of a fortress. There's no entrance fee but you'll have to pay to park. The market neighborhood is a pleasant exploration, Atpazari Square, and the oldest mosque in Ankara, Alaadin Camii, has some Roman ruins built into the surroundings.