More and more every day, valuable archival material is being digitized and made available on the web. Sometimes this leads to exciting discoveries for people like me. Here's an example.
British Pathé, a newsreel company, recently put thousands of their historical films on YouTube. Openculture calls it "a goldmine of footage."
One of their films features MIT's Solar House IV, built by Hoyt Hottel, Lawrence B. Anderson and their team in 1957-58. It's short, but significant.
Solar House IV is discussed in great detail in The Solar House.
Related: Hoyt Hottel's skepticism