The roman baths in Ankara are worth a half hour of your time. It is only a 3TL entrance fee and is not far north of the Ulus traffic circle on Ataturk Blvd (10 minute walk north of the circle).
The baths are somewhat impressive, although can not be enjoyed up close because of a protective fence around the main areas of the complex. The most interesting part of this site is the hundred or so roman gravestones that have been placed around the field leading up to the baths. Also, there are hundreds of broken pillars, headstones and bricks lying around that can be explored up close.
There is a distinct lack of people up on this hill, with a nice view. An interesting spot to go to on a nice afternoon. Enjoy!