One of the best tours in Belfast is free. At 11am and 2pm Monday to Friday there is a free tour of the Parliament Buildings at Stormont. The buildings date back to 1923 and is steeped in the colourful political history of Nothern Ireland. The best way of getting there is the CitySightseeing Belfast hop on hop off bus that runs from the city centre every 30 minutes.
The small cafe there is also a great place to get a tea or coffee with a scone, the cheapest you will find in Belfast too.