I was just wondering what the history was of the Blue Palace or Castle Solitude as it was referred to in old texts. The Wikia claims "It is built on the ruins of the old palace, which was destroyed by a fire".

What was this fire they speak about? Is there an actual start and finish to this story? I would like to know every little detail of this old palace if possible, reference books would be appreciated. I have searched high and low and haven't seen anything I don't already know. Also strictly canon please.

If you're referring to The Elder Scrolls Wiki, you should avoid that. It has some factual errors and hearsay included in the articles. The Unofficial Elder Scrolls Pages (uesp.net) is a more accurate wiki-like source, has separate game and lore articles, and is better at citing sources.

Yeah, it didn't make sense. If it was really destroyed by a fire then Magnus wouldn't have moved in with Pelagius after Potema's defeat. They probably just cleaned out the undead, painted it blue and called it a day.