British Bankers Association
The British Bankers Association (BBA) is a good place to start searching for historical libor rates. The agency calculates a base rate itself by counting a number of indications such as the libor rate itself. It then circulates its rate in the world through newswire, and banks globally. If you browse through the BBA website regularly you can know how libor rates move and fluctuate both ways and can thus have an idea about how you are going to be affected by it.
Financial Information Websites
There are many good financial information and news websites, at which libor rate is circulated frequently. Some of them are Bloomberg and Reuters, which cover the financial industry news comprehensively, and this includes the libor rate. By browsing these sites you may be able to find historical data on libor rates and how they have been fluctuating over a certain period in the past. By taking into consideration these rates, you can determine how the rates are going to move in near future.
Specialized Information Channels
If you are looking to find out the historical libor rate data for a specific reason, for example housing loan renegotiation, it is better to look for specialized websites. There are many business-to-business websites and online information portals that can guide you towards how you can find historical libor rate and how you can calculate it to find out its impact on your loan interest rate.