I have a degree in history. In fact I did graduate work in history, was a graduate assistant and everything. I've never used it in a professional capacity - can you imagine? But it has also never hurt to have it.
Anyway, one my minor irritations is people seem to think the words historic and historical mean the same thing, and they usually say historical. Obviously they're related but there is a difference.
Historic refers to an event, usually momentous. Historical refers to things that have happened in the past.
When you're talking about Barack Obama's election as president, that's historic. It's an event, something that will be remembered. 50 years from now, you can talk about it as a historical fact, something happened.
Buildings are usually historic. Documents are usually historical.
I'm not an expert in grammar. I'm no grammarian, nor even a grammaritician, and you'll have to forgive me, if in one of these little outbursts of mine, I commit grammarcide, or over grammarify things. I may have it wrong, in other words. But still, they are not interchangeable.
Oh, and don't never, ever, call me a history buff.