Bangalore Mountaineering Club (BMC) is organizing a trek to Kalwarbetta Trek during next two days (Feb24-25). It could be for members only, though. Check with them. Details on their website.
An excerpt on Kalwarbetta from their site follows: "Kalwarbeta, 60 Kms from Bangalore, is one the hill forts amongst the Nandi Hill ranges. The dilapidated walls of Tipu's fort can be found today on steep Kalavara Betta (Skandagiri), near the village of Kalavara History says this was a small but strong hill fort. It surrendered to British troops on 19 October 1791. It remained in British hands until the peace treaty of 1792, which concluded of the third Anglo-Mysore war. This is a tedious trek as the hill is precipitous and high. The trek starts from the Papagni Temple at the foothills of Kalwara village. The fortress of Kalwarbeta is in full sight throughout the walk uphill. This steep and fantastic trek through a maze of dense shrub is highly intriguing. Kalwarbeta is a teaser. Just as you reach the fort wall contended that you have topped the hill, you see another ring of fort. No sooner you reach there; you will find another majestic fort wall waiting to be conquered. There are six such series of stonewalls protecting an abandoned temple on the hilltop. "