The Feynman Lectures On Physics are known worldwide as a classic resource covering practically the entire domain (up to 1961-1963, the era in which the lectures were given) from the most basic principles of Newtonian physics through Einstein's general relativity, superconductivity, and quantum mechanics. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.