The BBC website is far bigger than any other site in the world. It's got over three million pages of information, which is several times the quantity of its nearest rivals.
As has been stated, many of the pages don't offer much 'depth' in the information provided. However, there are often links provided to external sites which can provide further information.
Several people on AB have been kind enough to compliment me on my web-searching skills. In many cases, the links that I've provided have been found by going through the BBC site. The section of AB where I refer to the BBC site most often, though, has to be 'Food & Drink'. This is because of the superb database of recipes that the BBC website provides.
Chris