Sofia Valley

The Sofia Valley (Bulgarian: Софийска котловина, transliterated as Sofiyska kotlovina) is a valley in central western Bulgaria, bordering Stara Planina to the northeast, the Viskyar, Lyulin, Vitosha and Lozenets mountains to the southwest, the Vakarel Mountain to the southeast and the low Slivnitsa Heights to the northwest.

After the valley's bottom was formed, the stream of the Iskar River was blocked and the whole valley became a lake, which is the reason for the gritty and clayey soils that cover most of the valley. The lake ceased to exist when the river drove through Stara Planina to form its present bed.

The Sofia Valley is rich in mineral springs, which are, together with the valley's predisposal to seismic activity, the result of its fault character.