Western Ghats Running Foundation offers two races in a calender year. The SRT Ultra, which takes you throught the beautiful trails and hills of Sinhagad, Rajgad and Torna forts, and promises you some tough time out there. You climb three of the most famous forts in Maharashtra, all three have a rich history and have recently been recognised as a part of World Heritage site by UNESCO. Be prepared to hike, crawl and walk through some very steep traverses. It happens every year in the second weekend of December.
The second one is The Sinhagad Epic Trail race. It explores the Sinhagad for in much detail and gives you the feel of a sky race.