Hampi Express that connects Bangalore and Hubli is a popular option to reach Bellary Fort from Bangalore. The train passes via Bellary, the nearest railway station from Bellary Fort. Both the up and down journeys the train covers in the night, a major reason for its popularity.
There are no luxury buses connecting Bangalore to Bellary Fort, only one Rajahamsa is available . If possible avoid roadways as its quite impossible to avoid traffic jams.
Bellary Fort is about 300 kms from Bangalore and the nearest railway station is Bellary Jn which is just a few minutes from Bellary Fort. If you are visiting only Bellary Fort and there about then using train as the mode of transport is the best option.