Ranganathaswamy temple: This is a 11th century temple built by Chola kings which was later renovated during Vijayanagar rule. This temple has carvings inside the temple and inscriptions about the history. More details and pictures here - http://arunthetraveller.blogspot.in/2011/06/rock-climbing-series-i.html
Someshwara temple: This has resemblance to the Someshwara temples at Ulsoor and the one in Kolar. So this must be initially built by the Cholas and later expanded by Kempegowda. There is also a watch tower built by Kempegowda which is similar to the Kempegowda towers in Bangalore.
Fort: The walls of the fort built by Kempegowda can still be seen near the bus stand area.
Kalya caves: Around 10 kms from Magadi, we come across natural caves and cave temples where saints were known to meditate during ancient times. It requires climbing a series of steps and at a few places climbing on the rocks. But the climb is not tough.
Savandurga: Famous for rock climbing, this also has a Lakshmi Narasimha Swamy temple at the foothills which is visited by many people. http://arunthetraveller.blogspot.in/2011/06/rock-climbing-series-i.html
How to reach: Magadi is well connected by road from Bangalore and can also be reached from Bangalore-Mangalore highway. From Magadi one can hire private auto/taxi to roam around the taluk.
Food/Accommodation: Very limited options available for food. Its advisable to carry food from home. Also no options available for stay.