Bhongir Fort is about 70 kms from Hyderabad (from Gachibowli area). It’s pretty much a single structure that’s the remnant of what-was-a-fort, built atop a massive rock. While the fort itself is okay-ish, the climb up the rock to get to the fort is pretty nice.
Here’s what Wikipedia has to say: Bhongir Fort was built on an isolated monolithic rock by the Western Chalukya ruler Tri-bhuvana-malla Vikram-aditya VI and was named after him as Tribhuvanagiri. This name gradually became Bhuvanagiri and subsequently Bhongir. It has a unique egg-shaped construction with two entry points protected by huge rocks, so the fort was considered practically impregnable by invading armies. The Bala Hisar or citadel on the top of the hill gives a bird’s eye view of the neighbouring area. According to legend, there once was an underground corridor connecting Bhongir Fort to Golconda Fort.