This type of linga is known as ekamukha (one-faced, also spelled ekmukha). The rock-cut caves at Udayagiri seem to have been the focus of a complex mixture of Shiva worship (inside), Vishnu worship (outside), sun worship, and astronomical activity including the prediction of monsoons. Udayagiri is also the original site of the famous iron pillar of Chandragupta II which is now in Delhi. The "caves" themselves are quite shallow. Some are mere niches which are open to the outdoors, while others are accessed by small entrances cut into the rock face.