Gavi Gangadhareshwara Temple, Bangalore
The temple is famous for a scientific reason too. Being a cave, the presiding deity Shiva is inside the cave. There is no way the sun rays could enter the cave. But on Makarsankranthi day (starting of Utharayana kala) the suns rays falls on the Shiva linga. The temple has been carved out and the deity has been placed in such a manner that only on this occasion that sun rays enter the temple. People throng in huge numbers to witness this marvellous sight.
Apart from this wonder, the cave temple is a must watch. The cave is believed to be at least 3000 years old. It is also said that Sages Gowthama and Bharadwaja has done penance in this cave. This natural cave formation is a great place to visit. To circumvent/do a pradakshina of the deity one has to be really low as the passage is about 4-5 feet in height.
There are also two passages which are believed to be leading to Kashi and Shivaganga respectively. This place is not properly managed, and there is stink coming out of this way.
Outside the temple are huge stone structures of a Trident, Damaru (musical instrument), two stone discs can be found on the compound. These structures has been believed to be dating back to 9th Century.
Kannada news channel, TV 9 has a special report on this: (Audio is Kannada)
Whenever you are in Bangalore, plan a visit to this temple.