Pessinous is situated centrally on the Anatolian plateau, about 150 km southwest of the Turkish capital Ankara.
A major part of the ancient city is situated below the sleepy village of Ballıhisar ('Bal' = honey, 'hisar' = fortress), at ca. 950 m altitude. The nearest city is Sivrihisar. The continental climate ensures hot, dry summers and cold winters.

Ballıhisar lies in the valley of the Gallos with its many springs, a small river that runs dry in summer, but that in spring carries large volumes of water to the Sakarya (Sangarios) to the south.

Some kilometres to the northeast of Ballıhisar there is a mountain range with the 1820 m peak of the Dindymos (Arayit or Günyüzü Dağı). Although there are some springs in the area, vegetation is poor. The plateau surrounding the mountain range with abundant limestone and marl is heavily eroded at the ridges of the valleys, which makes the substratum clearly visible.

On the plateau mainly grain crops are grown, while in the valleys there are also pastures and orchards. Shepherds take their large flocks of sheep to the heavily grazed hills. Ballıhisar is a traditional agricultural village, with whitewashed farmhouses and a market place in its centre. At dawn and dusk the village is overrun by flocks of sheep which take turns at the well.